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  • 1
    Electronic Resource
    Electronic Resource
    The spatial distribution of fixed mutations within genes coding for proteins (1983)
    Springer
    Journal of molecular evolution 19 (1983), S. 437-448 
    Details
    ISSN: 1432-1432
    Keywords: Base substitution patterns ; Mutability ; Poisson density ; Geometric density ; Negative binomial density ; Natural selection ; Amino acids ; Proteins ; Genes ; Nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have examined the extensive amino acid sequence data now available for five protein families — the α crystallin A chain, myoglobin, alpha and beta hemoglobin, and the cytochromesc — with the goal of estimating the true spatial distribution of base substitutions within genes that code for proteins. In every case the commonly used Poisson density failed to even approximate the experimental pattern of base substitution. For the 87 species of beta hemoglobin examined, for example, the probability that the observed results were from a Poisson process was the minuscule 10−44. Analogous results were obtained for the other functional families. All the data were reasonably, but not perfectly, described by the negative binomial density. In particular, most of the data were described by one of the very simple limiting forms of this density, the geometric density. The implications of this for evolutionary inference are discussed. It is evident that most estimates of total base substitutions between genes are badly in need of revision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02102319
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  • 2
    Electronic Resource
    Electronic Resource
    Equilibrium folding pathways for model proteins (1983)
    Springer
    Journal of statistical physics 30 (1983), S. 549-559 
    Details
    ISSN: 1572-9613
    Keywords: Proteins ; conformations ; folding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Protein conformations have been generated with both a Monte Carlo scheme and a simpler two-state noninteracting globule-coil model. Conformational energies are taken to consist of intraresidue and interresidue terms. Interresidue energies are taken to be proportional to the number of nativelike contacts. To describe probable folding pathways, either energy or the number of native residues are employed as simple one-dimensional folding-unfolding coordinates. By considering only conformations at each point on these coordinates, it is possible to obtain detailed conformational descriptions of relatively rare intermediates on the folding pathway. This technique of “trapping” intermediates and statistically characterizing them is useful for studying conformational transitions. Equilibrium folding-unfolding pathways have been constructed by connecting most probable conformations in order along the folding coordinate. Calculations with the noninteracting globule-coil model have been performed with details chosen to correspond to those in the Monte Carlo calculation for pancreatic trypsin inhibitor. Both pathways are similar. Theα helix appears prior to formation of the central beta sheet; beta sheet formation coincides with a large maximum in the free energy because of the attendant loss of conformational entropy. Subsequently the Monte Carlo method indicates two alternative pathways for growth toward either the amino or the carboxyl terminus, followed by completion of the native form. For the globule-coil model, the growth pattern differs somewhat, with the appearance of the single pathway for folding up to the carboxyl terminus prior to completion of folding. This difference may originate in the Monte Carlo sampling procedures or in the simplifications of the globule-coil model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01012328
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of adenylate cyclase and cAMP phosphodiesterase in the gastrulating chick embryo (1983)
    Springer
    Development genes and evolution 192 (1983), S. 42-44 
    Details
    ISSN: 1432-041X
    Keywords: Chick embryo ; Gastrulation ; Adenylate cyclase ; cAMP phosphodiesterase ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural localization of adenylate cyclase (E.C. 4.6.1.1.) and cAMP phosphodiesterase (PDE) (E.C. 3.1.4.17.) in the ectoderm of the developmental stage 4 chick embryo was studied. Adenylate cyclase was localized in the lateral surfaces of the ectodermal cells. In the primitive streak cells the enzymatic activity was observed on all the lateral surfaces, whereas in the periphery of the blastoderm the reaction product was localized in the apical parts of the lateral plasma membranes only. cAMP PDE localized in the apical cytoplasm of the ectodermal cells, with highest activity in the globular projections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848768
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  • 4
    Electronic Resource
    Electronic Resource
    Electron microscopical study of self-differentiation potency in the chick embryonic endoderm cultured in vitro (1983)
    Springer
    Development genes and evolution 192 (1983), S. 171-178 
    Details
    ISSN: 1432-041X
    Keywords: Differentiation ; Digestive tract ; Endoderm ; Organ culture ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The self-differentiation potency of the endoderm of the chick embryo was investigated mainly by transmission electron microscopy. Endodermal fragments isolated from 4- to 6-day stomach or small intestine were cultured in the absence of mesenchyme and were able to differentiate in vitro into organ-specific epithelia. Endodermal fragments isolated from the stomach region differentiated into a pseudo-stratified epithelium with periodic acid Schiff-positive mucous granules in the apical cytoplasm, while those from the small intestinal region differentiated into a simple columnar epithelium with a striated border which was positive in alkaline phosphatase activity. These features are comparable with those of the mucous secretory epithelium of the normal embryonic stomach and the absorptive epithelium of normal embryonic small intestine, respectively. Next, the self-differentiation potencies were investigated of the upper and lower layers of the blastoderms, at stages 1–5 of Hamburger and Hamilton (H. and H.). Both stomach-type and small-intestine-type epithelia developed only when fragments of the lower layer isolated from the blastoderms older than stage 3 of H. and H. were cultured, suggesting that cells possessing the potency to differentiate into the stomach- and small-intestine-type epithelia exist in the definitive endoderm at the beginning of its formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848687
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of tuberculate spores in Streptomyces thermoviolaceus (1983)
    Springer
    Archives of microbiology 134 (1983), S. 295-298 
    Details
    ISSN: 1432-072X
    Keywords: Actinomycetes ; Streptomyces thermoviolaceus ; Sporogenesis ; Spore ornamentation ; Cupular knobs ; Sheath ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sporogenesis of aerial spores in Streptomyces thermoviolaceus corresponded to a common sporulation type in the genus. The sporulation septum was composed of an outer ring-shaped constriction wall and an inner interspace septum arising by the inwards growth of a double annulus. In mature spores the wall was composed of two layers, the outer one was part of the parent hyphal wall and septum material, the inner one was formed de novo. The spore chains were enclosed by the thin breakable sheath containing small rod-like elements. The ornamentation in the form of knobs, which were a characteristic feature of the species originated from the sheath. The knobs were hemispherical particles with an inner electron dense core and an outer electron transparent shell. The term “cupular knobs” was suggested for this type of tuberculate ornamentation. Frequently, the knobs became detached from the surface in which case the inner core separated easily from the shell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407805
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  • 6
    Electronic Resource
    Electronic Resource
    Chroococcus S24 and Chroococcus N41 (cyanobacteria): morphological, biochemical and genetic characterization and effects of water stress on ultrastructure (1983)
    Springer
    Archives of microbiology 135 (1983), S. 81-90 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Nitrogen fixation ; Water stress ; Taxonomy ; DNA ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two strains of desiccation-tolerant coccoid cyanobacteria, Chroococcus S24, a marine form, and Chroococcus N41, a cryptoendolith isolated from a hot-desert rock, have been characterized. The mol % DNA base compositions of the strains are 47.1 and 48.9% respectively. Plasmid DNA was not detected in either strain. The pigment contents and nutritional characteristics of the strains are identical. Both lack phycoerythrinoid pigments and, in culture, behave as slow-growing halotolerant marine forms with elevated requirements for Na+, Cl−, Mg2+ and Ca2+. Sucrose was the only carbon source of those tested that supported photoheterotrophic growth. Each strain synthesizes nitrogenase under anaerobic conditions but not in air. Morphologically the two strains are indistinguishable. They are considered to be independent isolates of the same cyanobacterial species. Chroococcus N41 was studied in detail with the electron microscope. When brought to equilibrium at matric water potentials of-168 MPa and lower (to-673 MPa=c0.12a w) the protoplast shrinks, but the cells maintain the same size and diameter as those at-2,156 kPa (MN medium; control); the sheath expands and remains attached to the cell wall outer membrane by fibrils. The cell wall, cell membrane, thylakoid membranes, cyanophycin granules and carboxysomes appeared intact in desiccated cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408014
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructure of catecholamine-containing axons in the intestine of the domestic fowl (1983)
    Springer
    Cell & tissue research 234 (1983), S. 411-425 
    Details
    ISSN: 1432-0878
    Keywords: Intestines (chicken) ; Innervation ; Catecholamines ; Adrenergic fibres ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Axons in the duodenum, ileum and rectum of the domestic fowl were identified as catecholamine-containing (CA) on the basis of positive reactivity following chromaffin fixation for electron microscopy. CA-axons in association with blood vessels in all regions of the intestine and in non-vascular sites in the small intestine had a ‘ typical’ adrenergic appearance, in that they contained many small granular vesicles (SGV) and variable numbers of large granular vesicles (LGV). In the rectum the non-vascular CA-axon profiles were atypical, in that there were many elongated LGV and few SGV, and the chromaffin reactivity was weak. The nerve profiles in the rectum were dramatically reduced following 6-hydroxydopamine and reserpine treatment and were absent in rectum cultured in the absence of extrinsic ganglia. It was concluded that the profiles, in spite of their low chromaffin reactivity, truely represent CA-axons. The possibility was raised that the atypical morphology and reduced chromaffin reactivity is due to the presence of adrenaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213778
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructural identification of corticotropes of the fetal rat (1983)
    Springer
    Cell & tissue research 234 (1983), S. 427-437 
    Details
    ISSN: 1432-0878
    Keywords: Corticotropes ; Rat fetus ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Corticotropes of rat fetuses aged 16, 18 and 21 days were localized by the indirect antibody-enzyme method on semithin sections of the pituitary. The development of the ultrastructure of these cells was observed on consecutive ultrathin sections. In comparison with previous data our present results show that identification of a fetal cell type cannot be based entirely on morphological criteria. The structural peculiarities of corticotropes obtained from studies in vivo are compared with those observed in cells maintained in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213779
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  • 9
    Electronic Resource
    Electronic Resource
    Cyclophosphamide-induced changes in rodent odontogenesis (1983)
    Springer
    Cell & tissue research 234 (1983), S. 679-689 
    Details
    ISSN: 1432-0878
    Keywords: Odontogenesis ; Rats ; Cyclophosphamide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cyclophosphamide-induced changes in rodent odontogenesis were investigated by light and electron microscopy in four-day-old Sprague Dawley rats given one injection of 40 mg/kg of body weight of cyclophosphamide and killed at intervals of one hour, one day, one week and two weeks. Incisor and molar teeth were dissected from the animals, fixed in 2.0% glutaraldehyde in 0.1 M sodium cacodylate with 3.4% sucrose, and subsequently some were incubated for alkaline phosphatase reaction, and embedded in Spurr's medium for sectioning at light- and electron-microscopic levels. From three days a cell-sparse zone was created in the pulp in the growing end of the tooth and progressive cellular changes were observed which became more severe in the one-week and two-week specimens. Subodontoblast and adjacent pulpal cells were the most affected showing nuclear changes, damage to, or loss of, organelles, and inclusion bodies. Odontogenic epithelium was less affected and odontoblasts appeared to be unaffected by the drug. A new irregular matrix was laid down in the defect area and seemed to be the product of depolarized odontoblasts. This new matrix showed alkaline phosphatase activity, as did the cells embedded in it, and later it became mineralized. It is speculated that the polarity of odontoblasts might be maintained by an intact subodontoblastic layer; when this is lost the odontoblasts become depolarized and capable of secreting matrix from both ends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218659
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  • 10
    Electronic Resource
    Electronic Resource
    Isolation of metabolically active endothelial cells in high yield from bovine cavernous bodies (1983)
    Springer
    Cell & tissue research 232 (1983), S. 579-591 
    Details
    ISSN: 1432-0878
    Keywords: Cavernous bodies ; Endothelial cells ; Respiratory activity ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Work on endothelial cells has been limited by the availability of procedures for obtaining such cells in quantities adequate for direct in vitro analysis. The present paper describes a method for the isolation of endothelial cells from bovine cavernous bodies. A number of cells ranging from 2.5 to 4 × 108 per animal has been obtained. The cells were identified as follows 1) presence of the “Weibel and Palade” bodies in the isolated cells, 2) “cobblestone” appearance of cell cultures, and 3) presence of factor VIII, as demonstrated by immunofluorescence assays. The cell viability at the end of the purification procedure was tested 1) by dye-exclusion tests and 2) by metabolic assays. Features of this preparation are 1) the very high yield of viable endothelial cells, 2) the absence of contamination by fibroblasts and smooth muscle cells and a very low contamination by erythrocytes and 3) the fine dispersion of the isolated cells. These properties allow functional and subcellular fractionation studies on freshly isolated endothelial cells of microvascular origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216430
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  • 11
    Electronic Resource
    Electronic Resource
    Ultrastructural morphometry of the myocardium of Thunnus alalunga (1983)
    Springer
    Cell & tissue research 233 (1983), S. 427-438 
    Details
    ISSN: 1432-0878
    Keywords: Myocardium ; Thunnus alalunga ; Ultrastructure ; Mitochondria ; Myofibrils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The common ventricle in the heart of the Thunnus alalunga was studied. The ventricular myocardium consists of an outer compact layer and a thick inner spongy layer. The compact layer has slightly larger cells (4–6 μm diameter) than the spongy layer (2.5–5 μm diameter). Ultrastructurally the myocardium displays normal arrangements of myofibrils and mitochondria. The sarcoplasmic reticulum is poorly developed. The intercalated discs are simple with the fascia adherens being the most frequent junctional type observed; occasionally a desmosome was seen. Nexus type junctions are present but are unassociated with the intercalated discs. There are no t-tubules evident but the plasmalemma exhibits numerous caveolae which rarely form couplings with the sarcoplasmic reticulum. A morphometric analysis of the volume percent of mitochondria and myofibrils showed that the myocardial cells in the spongy layer of the heart have a significantly greater volume percentage of mitochondria than the compact layer. No significant differences were found between myocardial regions when the volume percentages of myofibrils were compared. The physiological studies revealed that the albacore tuna has heart rates (120 bpm) and ventricular blood pressures (100 mmHg) that are among the highest reported for fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238308
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  • 12
    Electronic Resource
    Electronic Resource
    Ultrastructural and immunohistochemical studies of rat epididymis (1983)
    Springer
    Cell & tissue research 233 (1983), S. 523-537 
    Details
    ISSN: 1432-0878
    Keywords: Epididymis (rat) ; Myosin ; Actin ; Fibronectin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anatomical distribution of smooth muscle actin, myosin, fibronectin and basement membrane has been investigated immunohistochemically, using the indirect immunofluorescence technique, in the rat epididymis. The findings were correlated with the ultrastructural organization of the organ. Actin was found to be distributed in the stereociliary region of the epithelial principal cells and in the terminal web region. Actin was also visible along the base of the epithelium. Myosin was detected in the terminal web and in the terminal bar regions of the epithelium. The contractile cells showed a strong stain for both proteins. Basement membrane immunoreactivity was distributed along the epithelial basement membrane and around the contractile cells of the wall. In the cauda, between the epithelium and the contractile cell layers, the lamina propria, containing blood vessels and a thin layer of cells, was negative for all antigens investigated. Fibronectin showed a granular distribution around the contractile cells, mainly in the cauda. The ultrastructural study showed only thin (5–6 nm in diameter) filaments in the stereocilia and terminal web region. Thin filaments were also visible in the cytoplasm of the basal cells, thus suggesting a contractile function of this cell type. The heterogeneous appearance of the contractile cells of the wall seemed to support the different contractile pattern of the epididymal regions: caput, corpus and cauda. The cells present in the lamina propria showed cytoplasmic vesicles with dark granules resembling the “A” cell granules of the endocrine pancreas and gut mucosa cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212222
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  • 13
    Electronic Resource
    Electronic Resource
    The structure and function of the nematocysts of Chironex fleckeri Southcott, 1956 (1983)
    Springer
    Cell & tissue research 233 (1983), S. 563-577 
    Details
    ISSN: 1432-0878
    Keywords: Nematocysts ; Structure ; Ultrastructure ; Function ; Cubozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microbasic p-mastigophores, euryteles of two size groups, holotrichous isorhizas and atrichous isorhizas, comprise the cnidom of Chironex fleckeri, a cubozoan that has been responsible for several human fatalities. In its undischarged state each microbasic mastigophore of C. fleckeri consists of a capsule containing matrix and an inverted tube possessing a smooth-walled butt which is loosely coiled helically and which narrows to form a thread that is tightly coiled helically and markedly pleated. Both butt and thread carry three helices of spines and contain a granular matrix. During discharge, the proximal butt spines form initially a piercing stylet. Granular material from the butt and thread is released prior to the release of capsular material. Each eurytele possesses a tube with a butt composed of three bulbs, the middle bulb bearing long spines. Each holotrichous isorhiza possesses a coiled tube bearing small spines along its length. Each atrichous isorhiza exhibits a tube that is devoid of spines and loosely folded in the undischarged condition. The probable role of each type of nematocyst is inferred from its structure and features that enable the ready separation of the nematocysts of C. fleckeri from those of scyphozoan jellyfish are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212225
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  • 14
    Electronic Resource
    Electronic Resource
    Ciliary epithelia of the mammalian eye in cultured explants (1983)
    Springer
    Cell & tissue research 233 (1983), S. 629-638 
    Details
    ISSN: 1432-0878
    Keywords: Ciliary process ; Cultured explant ; Epithelial cells ; Ultrastructure ; Bovine and rabbit eyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characteristics of ciliary epithelium from bovine, pigmented rabbit, and fetal albino rabbit were studied in cultured explants. The tips of ciliary processes were cultured in plastic dishes with Dulbecco Modified Eagle Medium (DMEM) containing 5% fetal bovine serum. More than half of the expiants adhered to the plastic culture dish, and epithelial cells spread as monolayers within a few days. Initially the explant contains two layers, the outer (nonpigmented cells) and the inner (pigmented cells). Later the explant exhibits three layers: 1) outermost lightly pigmented flattened cells, 2) an outer layer of nonpigmented cells, and 3) an inner layer of densely pigmented cuboidal cells. The cells of the outermost layer are continuous with the cells of the inner layer. A narrow space lies between the outermost layer and the outer layer. The columnar cells in the outer layer contain well developed organelles but no pigment granules; they possess a basement membrane, lateral interdigitations, and junctional complexes near their apices. Numerous focal junctions and some ciliary channel-like structures were detected between the columnar cells of the outer layer and the cuboidal cells of the inner layer. The cuboidal cells of the inner layer are filled with pigment granules. These observations suggest that the columnar cells of the outer layer are nonpigmented epithelium, the cuboidal cells of the inner layer are pigmented epithelium, and the flatened cells in the outermost layer are derived from pigmented epithelium.
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    URL: http://dx.doi.org/10.1007/BF00212230
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  • 15
    Electronic Resource
    Electronic Resource
    Ultrastructural observations on the formation of follicles in the human fetal thyroid (1983)
    Springer
    Cell & tissue research 233 (1983), S. 693-698 
    Details
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Human fetus ; Follicles ; Ultrastructure ; Differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Thyroid glands from 40 human fetuses ranging from 30 to 175 mm in length were examined by electron microscopy. At the 30 mm stage, the cells are arranged in cords or clusters and contain numerous free ribosomes. The rough-surfaced endoplasmic reticulum (RER) is poorly developed and the Golgi complex consists of saccules, smooth and coated vesicles. Mitochondria, microfilaments, glycogen particles, occasional lysosome-like structures, and single cilia are observed. At sites of incipient follicle formation, intercellular clefts containing interdigitating microvilli, delimited by junctional complexes, are evident. In addition, the apical region of some cells contains vacuoles. At the 50-mm stage, intercellular clefts are more apparent, some of them organized into small follicles through the enlargement of the lumen, the incorporation of additional cells, and the formation of a basal lamina. With increasing gestational age, more follicles are established. The lumina vary from round to clover-leaf shaped and have an electron-dense content. Cisternae of RER are dilated and contain flocculent material. The Golgi complex is more extensive, and lysosome-like structures are more numerous. By the 100-mm stage, the follicular cells appear morphologically well differentiated. The results demonstrate an extracellular origin of the follicular lumen in the human fetal thyroid.
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    URL: http://dx.doi.org/10.1007/BF00212236
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  • 16
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    Electronic Resource
    Ultrastructural immunocytochemical localization of fibronectin in the developing rat lung (1983)
    Springer
    Cell & tissue research 234 (1983), S. 165-177 
    Details
    ISSN: 1432-0878
    Keywords: Fibronectin ; Lung ; Development ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In a previous study changes in the macrodistribution of fibronectin during rat-lung development were examined. Using the peroxidase-antiperoxidase immunocytochemical technique, we have demonstrated the presence of fibronectin in embryonic, neonatal, and adult rat lung at the ultrastructural level. In the embryo, fibronectin is found both in an intra-and extracellular association with isolated pneumoblasts, and in a periodic distribution along the basal lamina. The neonate displays fibronectin in an intracellular association with early type-I cells and on their basal and luminal surfaces, but not in association with type-II cells. Neonatal basal lamina is diffusely labeled by anti-fibronectin antiserum. Fibronectin in adult tissue is found both intracellularly and on the basal and luminal surfaces of type-I cells but not in type-II cells. The basal lamina and interstitial connective tissue are slightly or non-reactive. These observations confirm and extend our initial suggestion that fibronectin is involved in rat-lung development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217410
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  • 17
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    Electron microscopy of extracellular materials during the development of a sea star, Patiria miniata (Echinodermata: Asteroidea) (1983)
    Springer
    Cell & tissue research 234 (1983), S. 193-200 
    Details
    ISSN: 1432-0878
    Keywords: Sea star ; Development ; Cuticle ; Extracellular materials ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of conspicuous extracellular materials during the life history of a sea star (Patiria miniata) is described. The outer surface of the developing sea star is covered by two morphologically different cuticles that appear sequentially during ontogeny. The primary cuticle, which is about 120 nm thick and two-layered, is present from mid-blastula through the end of the larval stage. The secondary cuticle, which is about 1 μm thick and three-layered, first appears on the epidermis of the rudiment region of the larva and, after metamorphosis, covers the entire epidermis of the juvenile and adult stages. During ontogeny, there are only two conspicuous gut cuticles: the first lines the newly invaginated archenteron at the start of the gastrula stage, and the second lines the esophagus during the larval stage. A blastocoelic basal lamina first appears at mid-blastula and persists as subectodermal and subendodermal basal laminae. Ruthenium red-positive granules are detectable between the lateral surfaces of adjacent ectodermal cells during part of the gastrula stage; this transient intercellular material may possibly aid in lateral adhesion between cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217412
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  • 18
    Electronic Resource
    Electronic Resource
    Changes in plastid ultrastructure during iron nutrition-mediated chloroplast development (1983)
    Springer
    Protoplasma 114 (1983), S. 85-92 
    Details
    ISSN: 1615-6102
    Keywords: Chloroplasts ; Iron stress ; Sugar beet ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When grown in iron-free media, the youngest leaves of healthy green sugar beet plants became completely yellow after 6 to 8 days. This chlorosis was quickly reversed by resupplying iron. A study of the ultrastructure of the iron -stressed leaves revealed apparently normal subcellular organization except for the plastids which were small and undeveloped, contained a rudimentary, disorganized grana-fretwork and clusters of vesicles in the periphery. Twelve to 16 hours after resupply of iron, aggregates of phytoferritin were observed in the stroma, and the granal fretwork underwent further development. There was an increased orientation of the membranes along the long axis of the plastids and an increase in the length of the individual grana stacks. By 48 hours, leaf chlorophyll content was about 40% of the control. At the ultrastructural level, parallel alignment of membrane orientation was complete and the grana stacks began to increase in the number of thylakoids per stack.
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    URL: http://dx.doi.org/10.1007/BF01279871
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    Nucleolus-associated bodies (karyosomes) in dividing and differentiating plant cells (1983)
    Springer
    Protoplasma 115 (1983), S. 1-10 
    Details
    ISSN: 1615-6102
    Keywords: Brassica napus ; Nucleolus ; Pisum sativum ; Ultrastructure ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The karyosome is a spherical body up to 1 μm in diameter that lies on the nucleolus of certain plant species, particularly those with a relatively low nuclear DNA content and an areticulate nuclear structure. It can be seen in the light microscope after impregnation with silver; in the electron microscope its structure consists of fibrillo-granular material. Nucleoli of cells in root apices may bear 0, 1, or 2 karyosomes. The frequency with which these numbers of karyosomes are observed depends on the location of the cells within the apex. In roots ofPisum sativum andZea mays the nucleoli of both slowly-dividing and young differentiating cells bear karyosomes more frequently than the nucleoli of rapidly-dividing cells. The karyosome seems to adopt a preferred location on the nucleolus, lying most frequently on the nucleolar surfaces directed towards the apex or base of the root. The origin and functional significance of the karyosome are discussed. Morphological evidence suggests that it may be material that formerly was part of a fibrillar centre.
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    URL: http://dx.doi.org/10.1007/BF01293574
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    Stomatal pore and cuticle formation inFunaria (1983)
    Springer
    Protoplasma 116 (1983), S. 1-13 
    Details
    ISSN: 1615-6102
    Keywords: Cuticle ; Peristomatal transpiration ; Stomata ; Ultrastructure ; Funaria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cuticle and pore development in the guard cells ofFunaria were investigated with the electron microscope. Pore cuticle formation is simultaneous with the creation of the pore itself. The morphology of the pore cuticle is unlike that of any cuticle described in the literature. It has many lamellae which are penetrated by electron dense fibrils. Three different cuticular morphologies exist from the pore to the subsidiary cell walls. The cuticles on the pore and outer walls contain fibrils that sometimes reach to the surface. The subsidiary cell cuticle lacks fibrils altogether. It is hypothesized that (1) cuticularization of the middle lamella contributes to ventral wall separation and (2) differences in extent of cuticular fibrils are related to greater water loss from stomata than from subsidiary cells (peristomatal transpiration).
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    URL: http://dx.doi.org/10.1007/BF01294225
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    Microtubule organization and morphogenesis in young spores of the mossTetraphis pellucida Hedw (1983)
    Springer
    Protoplasma 116 (1983), S. 115-124 
    Details
    ISSN: 1615-6102
    Keywords: Microtubules ; Moss ; MTOC ; Sporogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubule systems appear sequentially at the distal and proximal poles of tetrad members during mid-sporogenesis in the mossTetraphis pellucida Hedw. The distal microtubule system emanates from a microtubule organizing center (MTOC) located between the single plastid and the nucleus. The distal MTOC and associated microtubules, which appear immediately after cytokinesis, are ephemeral and do not appear to be associated with the deposition of exine occuring at the same time. The proximal microtubule system, which appears slightly later than the distal system, is a more stable component of mid-sporogenesis. The proximal MTOC is an irregularly lobed, patelliform aggregation of electron-dense granules located beneath the plasma membrane at the proximal spore pole. Several bundles of microtubules radiate from the proximal MTOC and traverse the cell, enclosing the nucleus in an cone of microtubules. The proximal microtubule system is thought to function in aperture development and organelle migration. The relatively large nucleus migrates a short distance in the small spore early in the tetrad stage and maintains its acentric position at the proximal pole throughout later stages of sporogenesis. The plastid migrates later in the tetrad stage from its meiotic position parallel to the distal surface to a position perpendicular to the distal surface with one tip in close proximity to the proximal MTOC. The proximal microtubule system reaches its maximum development by the end of the tetrad stage and all micrographic evidence of it is lost in the maturation stages of late sporogenesis.
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    URL: http://dx.doi.org/10.1007/BF01279828
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    Morphogenesis of coremia and rhizomorphs in the AscomyceteSphaerostilbe repens (1983)
    Springer
    Protoplasma 116 (1983), S. 99-114 
    Details
    ISSN: 1615-6102
    Keywords: Sphaerostilbe repens ; Ultrastructure ; Differentiation ; Coremia ; Rhizomorphs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The differentiating stages of coremia and rhizomorphs inSphaerostilbe repens were studied by transmission electron microscopy. Vegetative mycelium is characterized by highly cytoplasmic cells rich in ribosomes and mitochondria and with few vacuoles as well as endoplasmic reticulum. Cell walls are thin attaining a maximum thickness of 0.10 μm. During the aggregating phase a prosenchymatous mass of randomly oriented cells is produced by localized elongation and branching of the filaments. The hyphae in this region have the appearance of actively metabolising cells. In the course of the differentiating phase, numerous hyphae of the median zone of the aggregate grow upward and downward to give rise to coremium and rhizomorph primordia respectively. The individual hyphal tips lay parallel to each other and cells of the growing apices retain their meristematic characteristics. At the periphery of the aggregate and to a lesser extent in the subapical rhizomorphic zone, cells reduce their cytoplasmic density as a consequence of a decrease in the number of ribosomes. These cells also increase in size and become isodiametric and vacuolated. During cellular differentiation walls increase steadily in thickness and at the elongating phase they reach 0.30 μm in the rhizomorphic cortex. Mucilaginous material is progressively deposited around hyphae and in the most differentiated zones, coalesce to fill interhyphal spaces. This extracellular matrix seems to play a role in maintaining cohesiveness of the aggregated organs. The tissue in the process of differentiation is scattered with cells highly enriched in mitochondria and with cells virtually undifferentiated. Accumulation of microfilaments takes place in the differentiating zone localized behind the immersed meristematic apex. These structures might be involved in wall synthesis. Glycogen rosettes accumulate in the vegetative mycelium surrounding the aggregating centers, suggesting the possibility of supplying energy during the differentiating processes. The vacuolar system, represented by autophagic vacuoles which are present until the differentiation phase, presumably may also participate in the biochemical changes that occur during aggregation. Coremial cells are characterized by an increase in wall thickness, a highly sinuous plasma-membrane as well as large amounts of mucilaginous compounds accumulated between hyphae, but in all other respects they resemble the cells of actively growing vegetative hyphae.
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    URL: http://dx.doi.org/10.1007/BF01279827
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    Ultrastructure of aerial stalk formation by the ciliated protozoanSorogena stoianovitchae (1983)
    Springer
    Protoplasma 116 (1983), S. 125-135 
    Details
    ISSN: 1615-6102
    Keywords: Ciliated protozoan ; Sorogenesis ; Extracellular matrix ; Secretion ; Extrusive organelles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sorogena stoianovitchae Bradbury andOlive is an unusual kinetophragminophoran ciliate characterized by the aggregation of individual trophic cells to form a multicellular sorogen that rises aerially from the medium surface to produce a sorocarp. A light and electron microscope study of sorogenesis revealed how the sorogenic cells produce the stalk. The feeding ciliates contain numerous subpellicular expansions of rough endoplasmic reticulum cisternae that are only one element of the secretory system necessary for stalk formation. Upon aggregation, the stalk secretory system develops further, initially with the proliferation of the subpellicular expansions. Then, during later aggregation and early sorogenesis, other secretory elements appear: stalk material vesicles, dense granule vesicles, and electron lucent vacuoles. These are all derived from the rough endoplasmic reticulum. Only the subpellicular expansions and stalk material vesicles appear to add to the stalk matrix. The dense granule vesicles could be precursors of the stalk material vesicles; the electron lucent vacuoles, which can be demonstrated to contain fibrillar material, are perhaps by-products of the secretory process. Sorogenesis inSorogena occurs by a mechanism unique among the stalk-producing protists that have been studied.
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    URL: http://dx.doi.org/10.1007/BF01279829
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    Stalk function during sorogenesis by the ciliated protozoanSorogena stoianovitchae (1983)
    Springer
    Protoplasma 116 (1983), S. 136-144 
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    ISSN: 1615-6102
    Keywords: Stalk ; Ciliated protozoan ; Sorogenesis ; Extracellularmatrix ; Ultrastructure ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The sorogenic cells of the haptorid ciliateSorogena stoianovitchae Bradbury andOlive secrete a hydrated, fibrillar matrix that becomes organized to form a stalk. This light and electron microscope study examines the role of the secreted stalk matrix in the development of the sorocarp. The stalk material is secreted as a compact clump or clumps of material that expands as it hydrates. The expanded stalk material is initially viscous, but soon, through dehydration or cross-linking, solidifies to form a sheath. The sheath is the outside layer of the stalk, provides structural support, and controls the expansion of the newly secreted stalk material. The sorogenic cells continue to secrete stalk material that expands once it is outside of the cell. The resulting expansion force is directed upward by the sheath, thereby moving the cells further above the surface. The continued dehydration of the sheath material provides an inwardly directed force that also contributes to the upward movement of the sorogen.
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    URL: http://dx.doi.org/10.1007/BF01279830
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    Ultrastructural demonstration of loss and recovery of cytochrome oxidase activity during and after heat induction of microcycle conidiation inNeurospora crassa (1983)
    Springer
    Protoplasma 116 (1983), S. 149-154 
    Details
    ISSN: 1615-6102
    Keywords: Cytochrome oxidase ; Cytochemistry ; Ultrastructure ; Neurospora ; Heat treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytochrome oxidase (EC 1.9.3.1) activity of conidia of wild-typeNeurospora crassa was detected cytochemically at the ultrastructural level by 3,′-diaminobenzidine (DAB) reaction during heat treatment at 46 °C and after shift down to 25 °C. At 46 °C the decrease in the enzyme activity was shown to be time-dependent (0–10 hours) in the progressively overswelling conidia. Gradual recovery of the DAB reaction occurred in mitochondria of conidia outgrowing conidiogenous germ tubes (microcycle conidiation) when shifted down to 25 °C. Inactivation of cytochrome oxidase was efficiently prevented during heat treatment in the presence of Tween 20. Such conidia no longer overswelled but still required shift down to 25 °C to produce germ tubes with delayed conidiogenous ability.
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    URL: http://dx.doi.org/10.1007/BF01279832
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    The effect of UV-B and UV-C radiation on sugar beet leaves (1983)
    Springer
    Protoplasma 117 (1983), S. 7-16 
    Details
    ISSN: 1615-6102
    Keywords: Beta vulgaris ; Chloroplast ; Ultrastructure ; Ultraviolet radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of UV-C (254 nm) and UV-B (290–320 nm) radiation on leaves ofBeta vulgaris L. at the ultrastructural level was investigated. Although the damage caused by UV-C radiation was more striking than that resulting from UV-B radiation, several structural changes were seen in the UV-B treated material. Generally the effects of UV-B and UV-C radiation were different, suggesting different mechanisms of action, discernible even at the ultrastructural level.
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    URL: http://dx.doi.org/10.1007/BF01281779
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    The ultrastructure of the formation and development of the amoeboid tapetum inArum italicum miller (1983)
    Springer
    Protoplasma 117 (1983), S. 116-129 
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    ISSN: 1615-6102
    Keywords: Pollen ; Amoeboid tapetum ; Arum italicum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A tapetum is found around all higher plant meiocytes and is thought to nourish them. It may, in turn, be influenced by their development. The mature tapetal membrane in amoeboid (or periplasmodial) tapeta, of whichArum italicum is an example, fits closely around the developing meiocyte. This description of tapetal ultrastructure starts from the meiotic prophase when the tapetum is still cellular and comprises two rows of cells on the inside of the tetrasporangiate anther. The radial walls of the still cellular tapetum start to dissolve during leptotene of the first meiosis. The lysis begins in the middle lamella in those areas penetrated by the most plasmodesmata. The walls in contact with the meiocytes on the other hand do not disappear until after the first meiosis. At telophase the now fused cytoplasmic tapetal mass begins to extend its joint plasmamembrane, amoeboid fashion, into the loculus. A cluster of microtubules can be seen at the apex of this intrusion apparently initiating or maintaining the shape of the invading plasmamembrane front. The tapetum now adheres closely to the microspores. The tapetal zone closest to the spores has a prominent population of microtubules and just a little ER, whereas the outer zone away from the spores contains all the other organelles. The inner zone, in a squash preparation, is not readily separated from the spores. The microtubules, at the middle microspore stage, are no longer to be seen in a circle around the microspores, but spread out with some lying orthogonal to the now-forming exine surface. In places the tapetal plasmamembrane begins to retract from the exine leaving roughly cone-shaped zones (spines) which become filled with fibrillar material. This material begins to be deposited on the exine surface. These “spines” are both PAS. and Coomassie-blue positive and susceptible to acetolysis.
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    URL: http://dx.doi.org/10.1007/BF01288350
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    The structure and histochemistry of sclerotia ofSclerotinia minor Jagger III. Changes in ultrastructure and loss of reserve materials during carpogenic germination (1983)
    Springer
    Protoplasma 117 (1983), S. 214-225 
    Details
    ISSN: 1615-6102
    Keywords: Histochemistry ; Sclerotia ; Sclerotial germination ; Sclerotinia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytoplasmic reserves and extracellular substances were progressively broken down and utilized during carpogenic germination of sclerotia ofSclerotinia minor. Glycogen, wall polysaccharides and polyphosphate granules were removed first from regions of the sclerotium distant from developing apothecia, while protein bodies near the base of apothecial stipes were hydrolysed before those further away. The number of profiles of mitochondria and endoplasmic reticulum in cortical and medullary hyphae increased at the onset of germination, indicating increased metabolism in the hyphae. In contrast to developing sclerotia, simple pores with Woronin bodies were frequent in walls and septa during germination. Hyphae that appeared to converge towards the base of apothecial initials retained their cytoplasm and organelles until late in germination and hydrolysis of their reserves was delayed; these are interpreted as translocatory hyphae, although further work is required to determine their role unequivocally. When apothecia were fully developed, hyphae throughout the sclerotium were empty and the walls and extracellular matrix of cortical and medullary hyphae had almost completely broken down.
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    URL: http://dx.doi.org/10.1007/BF01281825
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    Mitosis in the freshwater red algaBatrachospermum ectocarpum (1983)
    Springer
    Protoplasma 118 (1983), S. 56-70 
    Details
    ISSN: 1615-6102
    Keywords: Carposporophyte ; Cell division ; Mitosis ; Rhodophyta ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitotic ultrastructure was observed in meristematic cells of carposporophyte generations of the freshwater red algaBatrachospermum ectocarpum. Prior to nuclear division, cell elongation occurs resulting in the nucleus being located at the proximal end of the cell and separated by a large central vacuole from a distal “empty region” which the daughter nucleus eventually occupies. In late prophase, nuclear envelope-attached polar rings are situated adjacent to shallow nuclear invaginations. At prometaphase the nuclear invaginations extend deeply into the nucleus forming continuous cytoplasmic channels containing microtubules. Perinuclear ER and a typical equatorial chromosomal plate are formed by metaphase at which time the nuclear envelope lining the cytoplasmic channels has dispersed. Chromosomal and non-chromosomal microtubules converge at the poles where a single, large gap is seen in the otherwise intact nuclear envelope. Polar rings were not detected in the few mitotic cells observed beyond prometaphase but are thought to be present. During anaphase an interzonal midpiece is formed and the distal-most incipient daughter nucleus moves laterally past the central vacuole into the apical “empty region”. Features of mitosis inBatrachospermum are believed to be intermediate between those exhibited by the lower and higher orders of red algae, this being consistent with the taxonomic placement of the genus in theNemaliales, the least advanced order of the classFlorideophyceae.
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    The ultrastructure of nuclear bodies in interphase plant cell nuclei (1983)
    Springer
    Protoplasma 118 (1983), S. 95-103 
    Details
    ISSN: 1615-6102
    Keywords: Nuclear bodies ; Nucleolus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nuclear bodies are found in interphase nuclei of root apices of a number of plant species. They often show differences in structure and position relative to the nucleolus and this has led to an attempt to define two classes of body. However, in some species their separation into two classes on structural grounds alone breaks down, indicating that although they may occupy different positions within the nucleus they may in these particular cases be only different forms of the same body. The two extremes of the range of bodies examined represent what have been called “nucleolus-associated body” (karyosome) and “dense body”. The nucleolus-associated body is typically attached to, or adjacent to, the nucleolus. It is composed of fibrils 4–8 nm wide and often has an open structure showing compound threads or fibrils separated from each other by electron-lucent spaces. The dense body is more compact in structure and typically lies free in the nucleoplasm. Both types of body have an affinity for silver ions which, together with their staining reaction following treatment with EDTA, indicates that they consist of ribonucleoprotein. The characteristics of nuclear bodies found in different plant species have some relationship with the structure and DNA content of the interphase nucleus. Nucleolus-associated bodies are characteristic of species with an areticulate nuclear structure (2 C DNA content 〈6 pg), while dense bodies are common in species with a reticulate nuclear structure (2 C DNA content 〉6 pg). The possible functions of the two forms of nuclear body are discussed.
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    Ultrastructural polysaccharide localization in calcifying and naked cells of the coccolithophoridEmiliania huxleyi (1983)
    Springer
    Protoplasma 118 (1983), S. 157-168 
    Details
    ISSN: 1615-6102
    Keywords: Calcification ; Coccolithophorids ; Polysaccharide localization ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Emiliania huxleyi is a marine coccolithophorid which produces coccoliths,i.e., particles consisting of calcite and macromolecular organic material. The coccoliths are formed intracellulary in specialized organelles which comprise a coccolith vesicle (CV) and a reticular body (RB), together forming the CV/RB system or calcifying system. After termination of calcification, the coccolith is extruded and incorporated into the coccosphere,i.e., one or several layers of extracellular coccoliths surrounding the cell. Apart from the coccolith-producing cells (C cells) ofE. huxleyi, there are naked cells (N cells) which seem to have lost the capacity to produce coccoliths but are very similar to the C cells in other morphological respects. Biochemical studies have revealed that polysaccharides may play a regulatory role in calcification. The aim of the present study was to determine the localization of polysaccharides in both C and N cells electron microscopically. For this purpose, a cytochemical staining technique according toThiéry (1967) was applied. The CV/RB system of C cells was conspicuously stained. Due to the excellent stainability of this system, a putative succession of morphological stages during coccolithogenesis could be described. The staining pattern of the N cells closely resembled that of the C cells. It was found, however, that the “calcifying” system of N and C cells differed in both morphology and position. It is suggested that the divergent morphology of the “calcifying” system of N cells accounts for its failure to produce coccoliths.
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    Biomimetic approach to the design of a pyridoxal enzyme model, 3Part 2: cf.1. Synthesis of 4-formyl-3-hydroxy-5-methacryloylaminomethyl-2-methylpyridine and its 5′-N-methylated analogue (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1-7 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of 4-formyl-3-hydroxy-5-methacryloylaminomethyl-2-methylpyridine (7a) and 4-formyl-3-hydroxy-5-(N-methacryloyl-N-methyl)aminomethyl-2-methylpyridine (7b) is reported. The intermediate products 5-aminomethyl-2,2,8-trimethyl-2H,4H-[1,3]-dioxino[4,5-c]-pyridine hydrochloride (3a), 2,2,8-trimethyl-5-methylaminomethyl-2H,4H-[1,3]-dioxino[4,5-c]-pyridine hydrochloride (3b), 5-methacryloylaminomethyl-2,2,8-trimethyl-2H,4H-[1,3]-dioxino-[4,5-c]pyridine hydrochloride (5a), 5-(N-methacryloyl-N-methyl)aminomethyl-2,2,8-trimethyl-2H,4H-[1,3]-dioxino-[4,5-c]pyridine hydrochloride (5b), 3-hydroxy-4-hydroxymethyl-5-metha-cryloylaminomethyl-2-methylpyridine (6a) and 3-hydroxy-4-hydroxymethyl-5-(N-methacryloyl-N-methyl)aminomethyl-2-methylpyridine (6b) were isolated and identified.
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    URL: http://dx.doi.org/10.1002/macp.1983.021840101
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    Polymerization of lactams, 53Part 52: cf.1. Anionic polymerization of 2-pyrrolidone accelerated with CO2, part 2 (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 41-57 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of 2-pyrrolidone (3) initiated with its potassium salt (1) (2-oxo-1-pyrrolidinylpotassium) and carbon dioxide was studied under optimal conditions. On the basis of a detailed experimental analysis, it is suggested to consider the investigated polymerization in the presence of gaseous CO2 as an accelerated non-activated polymerization. Alkali 2-oxo-1-pyrrolidine carboxylate, which is formed in the system by reaction of CO2 with 1, probably does not take part directly in the polymerization process and excerts only a controlling role.
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    Preparation of 5-hydroxy-7-methoxy-2,2-dimethyl-6-octyl(and 8-octyl)-4-chromanones and their Properties as UV Absorbers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 71-76 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 5-Hydroxy-7-methoxy-2,2-dimethyl-6-octyl(and 8-octyl)-4-chromanones (2a and 2b) were synthesized via 5,7 dihydroxy-2,2-dimethyl-6-octyl (and 8-octyl)-4-chromanones (1a and 1b) from phloroglucinol as a starting material. Cyclohexane solutions of 1a, 1b, 2a, and 2b were irradiated. The photostability of 2a and 2b was found to be better than that of 1a and 1b. Poly(vinyl chloride) film containing 6, 7 wt.-% of 2b was found to be most stable against photooxidation.
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    URL: http://dx.doi.org/10.1002/macp.1983.021840108
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    OH Radical-induced chemical reactions of polynucleotide complexes (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 165-173 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(A + U), the 1:1 complex of poly(riboadenylic acid), poly A, and poly(ribouridylic acid), poly U, at pH 8 and self-complexed poly A at pH 4 exist as double helices in dilute aqueous solution. These complexes exhibit a similar behavior as native calf thymus DNA upon irradiation with 16 MeV electron pulses. Thus time resolved Rayleight light scattering measurements showed that crosslinking and double strand breakage can be clearly separated, the former proceeding faster than the latter. The extent to which the two processes occur depends on the ionic strength of the solution. At ionic strenghts exceeding 10 -1 mol/l crosslinking is the dominant process indicating that hcrit, the critical length between two single strand breaks for the accomplishment of double strand breaks, is strongly reduced. The investigation of complexes of poly A and Mg2+ ions revealed that the destruction of salt bridges is the rate determining process for the decrease of the light scattering intensity due to mainchain scission. This implies that life-times of salt bridges can be determined.
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    URL: http://dx.doi.org/10.1002/macp.1983.021840117
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    The chemically initiated high pressure polymerization of ethylene (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 193-206 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of the high-pressure ethylene polymerization initiated by di-tert-butyl peroxide were measured via quantitative near-infrared spectroscopy at temperatures between 130°C and 165°C to a maximum pressure of 3 kbar. The overall polymerization rate was found to be first order in ethylene concentration and of the order 0,5 in peroxide concentration. The overall activation energy and the overall activation volume were determined to be E0 = 107,2 ± 7,5 kJ · mol-1 and Δ V0≠ = - 17,5 ± 5,0 cm3 · mol-1, respectively. From the overall quantities and from the decomposition rate of di-tert-butyl peroxide determined in independent spectroscopic high-pressure high-temperature experiments, kp · kt-1/2 (kp and kt are the propagation and termination rate constants, respectively) and the corresponding activation parameters, Ep - 1/2 Et and Δ vp≠ - 1/2 Δvt≠, were derived for the high-pressure ethylene polymerization. These data enable the overall polymerization rate to be determined also for high-pressure ethylene polymerizations initiated in any different way, provided the initiation rate law is known. The procedure is illustrated for the ethylene polymerization initiated by tert-butyl peroxypivalate.
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    Interaction between dyes and polyelectrolytes, 14Part 13: M. Shirai, M. Ohyabu, Y. Ono, M. Tanaka, J. Polym. Sci., Polym. Chem. Ed. 20, 555 (1982). Triplet energy transfer in a cationic dye-polyanion system (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 153-163 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Polymers with different fractions of azobenzene residues were prepared by radical copolymerization of methacrylic acid with 4′-phenylazomethacrylanilid. The triplet excitation energy transfer from methylene blue (1) to the azobenzene residues in the polymers was investigated by using the 1-photosensitized cis → trans isomerization of the azobenzene residue. The efficiency of the triplet excitation energy transfer from 1 to 4-(4′-phenylazoanilinocarbonyl)butanoic acid (4) as a monomer model compound. The number of azobenzene residues per polymer molecule and the molecular weight of the polymer were important factors for the efficient triplet excitation energy transfer. On addition of NaCl the energy transfer efficiency was lowered, suggesting that the binding of 1 to the polymer by electrostatic forces plays an important role. Binding of 1 to the polymers was investigated spectrophotometrically. Correlation with the binding of 1 to the polymers and the efficiency of triplet excitation energy transfer between 1 and azobenzene residues in the polymers is discussed.
    Additional Material: 8 Ill.
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    Untersuchung der teilschritte der ethylen-hochdruck-polymerisation, 1. Druckabhängigkeit der einzelnen geschwindigkeitskonstanten (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 207-216 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: In order to calculate the average molecular weight, the molecular weight distribution or the branching of low density polyethylene, the individual values of the rate constants of the different reactions involved in the free radical polymerization are required. The method of rotating sector was applied to determine the rate constants of chain propagation and chain termination in a wide range of temperatures and pressures. This first part of the work reports the influence of the pressure. It was found that the rate constant kp of the chain propagation increases with rising pressure whereas the rate constant kt of chain termination decreases. The effect of the pressure on kp can be explained in terms of the activation volume. The decrease of kt with pressure is caused by a diffusion controlled termination reaction.
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    On the mechanism of the flow process of poly(ethylene terephthalate) (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 217-223 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The mechanism of “flow process” defined as drawing by which neither crystallization nor molecular orientation takes place was clarified on the basis of its direct experimental evidences on drawing of “amorphous” poly(ethylene terephthalate) films. In a certain temperature range above Tg, the polymer molecules are deformed and oriented on drawing, “inter-molecular secondary linkage” playing an important role in the transmission of the applied force. When this intermolecular linkage breaks down above a certain critical temperature, the polymer molecules may slip past each other and flow independently, resulting in a large deformation without inducing any molecular orientation and crystallization. At higher temperatures crystallization occurs inducing the orientation as well.
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    Synthèse de polysiloxanes organofonctionnels, 1. Chloration des poly(diméthylsiloxane)s par le chlorure de sulfuryle (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 263-276 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Sulfuryl chloride was used as chlorination agent of poly(dimethylsiloxane)s (1) in order to obtain poly(dimethylsiloxane-co-chloromethylmethylsiloxane) and it was found to be more specific than molecular chlorine. Identification of chlorinated and chlorosulfonated units was shown to be possible by comparison of the results of 1H NMR spectroscopy with those obtained by GLC analysis of the mixtures obtained from octamethylcyclotetrasiloxane (2). After having shown that the distribution of the various types of methyl groups in 1 and 2, modified in this way, fits correctly a binomial law and that chlorosulfonated units can be hydrolysed, copolymers containing 20 to 25% of chloromethylated units and less than 2% of unwanted dichloromethylated units are accessible by use of this chlorination agent.
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    Liquid crystalline main chain polymers with highly flexible siloxane spacers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 253-262 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The synthesis and the phase behaviour of liquid crystalline main chain polymers are described. In these poly- and copolyesters the mesogenic units are linked by highly flexible oligodimethylsiloxane spacers. The comparison of their phase behaviour with that of polyesters known from the literature shows that dimethylsiloxane spacers as a replacement for alkyl spacers are leading to a drastic decrease of the transition temperatures. Depending on the length of the spacer glass transitions as low as -111°C can be achieved. The widths of the liquid crystalline phases thereby are retained up to a spacerlength of 13 oxydimethylsilanediyl (dimethylsiloxane) units. The homopolyesters mainly show smectic phases. In contrast to this nematic phases are found for copolyesters in which either the spacerlength or the mesogenic unit was varied. In one case a nematic phase was found over a temperature range of 311°C.
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    On the molecular weight determination by vapour pressure osmometry, 4Part 3: R. V. Figini, M. Marx-Figini, Makromol. Chem. 182, 437 (1981).. Experimental proof of the deviation of MVPO from Mn (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 319-322 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The kind of molecular weight average MVPO resulting from vapour pressure osmometry (VPO) measurements on solutions of paucimolecular polymer mixtures of different compositions is studied with a Hewlett Packard Model 302 B. Recent theoretical calculations which predicted that MVPO 〉 Mn are confirmed. The experimentally found quotient MVPOMn is between 1,04 and 1,26, being the greater, the greater is the polydispersity of the mixture, which is agreement with the former mathematical derivations.
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    Study of step-growth polymerizations using epoxy-carboxy reaction, 1. Study of the epoxy-carboxy reaction on models in solvents of low or medium dielectric constants (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 323-334 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Due to its importance in the field of block-polycondensation and of chemical modification, we carried out an extensive study of the epoxy-carboxy reaction on models. This papier is related to the reaction of benzoic acid with 1-phenoxy-2,3-epoxypropane in the presence of a basic catalyst, N,N-dimethyldodecylamine. It is carried out in low polar solvents (xylene, chlorobenzene, and o-dichlorobenzene); essential kinetic parameters are reported. From studies carried out under stoichiometric or non-stoichiometric conditions a general rate equation (υ = k [acid]0.5 [epoxy] [amine]) is obtained. Kinetic relations are the same, no matter what the catalyst is: dimethyldodecylammonium benzoate or free amine. From these kinetic data it results that the overall mechanism involves two steps.
    Additional Material: 8 Ill.
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    Polymer conformation and NMR chemical shifts, 7Part 6: cf. 10.. Conformational analysis of random copolymers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 371-381 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A method is developed for the conformational analysis of copolymers with randomly distributed stereo- and comonomer-sequences. The conformational probabilities of dyad sequences constituting a random copolymer chain are calculated as a function of the copolymer composition which is derived from the monomer reactivity ratios and the comonomer feed ratio. The applicability of this method is verified in the conformational analyses of poly(methyl acrylate-co-styrene) and poly(methyl methacrylate-co-styrene). The calculation indicates that the conformational stabilities of dyad sequences are scarcely dependent on the copolymer composition in the former copolymer, whereas they are susceptible to the composition in the latter copolymer. This conformational behavior apparently reflects the geometrical difference between the copolymers: the former is composed of two mono-substituted monomers and the latter of sterically nonequivalent monomers, viz. mono- and di-substituted vinyl compounds. The composition-dependences of 13C NMR chemical shifts of these copolymers are interpreted, based on the conformational calculation by this method.
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    Etude des prépolymères époxydes par chromatographie et 1H NMR à 350 MHz (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 411-429 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The epoxy resins (DGEBA) obtained from 4,4′-isopropylidendiphenol (bisphenol A) and 1-chloro-2,3-epoxypropane (epichlorohydrin) and synthetized by the “taffy” process were found to consist of oligomers. The composition of prepolymers could be deduced from gel permeation chromatography (GPC), and particularly by high pressure liquid chromatography (HPLC). In the more resolved HPLC spectrum each oligomer was found to be accompanied by satellite peaks. The functionality of the prepolymers, determined by 1H NMR spectroscopy and cryometric or vapour pressure osmometric measurements was found to be less than two. These phenomena are due to the existence of abnormal chain ends having no epoxy group. The structure of the main components spearated by preparative GPC was studied by 1H NMR. For the impurities, the two indentified structures of chain ends are primary and secondary alcohol functions. Finally the compositions of three DGEBA were determined.
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    Glass transition and melting temperatures of random copolyesters of poly(ethylene terephthalate) with p-hydroxybenzoic acid, 3Part 2, cf.: M. Balachandar, T. Balakrishanan, H. Kothandaraman, J. Polym. Sci., Polym. Chem. Ed. 20, 2621 (1982). (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 443-453 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The glass transition temperature of the random copolyesters of poly(ethylene terephthalate) and p-hydroxybenzoic acid prepared by molten state polycondensation increases with increasing concentration of p-oxybenzoate units (oxy-1,4-phenylenecarbonyl units). The observed values of the glass transition temperature are compared with the values predicted from various empirical equations on the Tg's of copolymers and the concave Tg composition curve is explained in terms of the internal stiffening effect of the p-oxybenzoate unit. The melting temperatures of the copolyesters vary with composition and show an eutectic phase diagram. The melting temperature and enthalpy of fusion of the homopolymer of p-hydroxybenzoic acid were determined making use of Flory's equation on the melting point of a copolymer.
    Additional Material: 6 Ill.
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    Untersuchung der teilschritte der ethylen-hochdruckpolymerisation, 2Teil 1: cf.1.. Druck- und temperaturabhängigkeit der einzelnen geschwindigkeitskonstanten (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 849-859 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: In the first part of this series the individual rate constants of the radical polymerization of ethylene are reported in dependency of pressure at 405 K. By further measurements under 500 - 1750 bar and 400 - 470 K, using again the method of the rotating sector, the dependency of the rate constants on both pressure and temperature was determined. With increasing temperature the rate constant of chain growth kp as well as that of chain termination kt increases. With increasing pressure, kp increases, whereas kt decreases because of the diffusion controlled termination reaction. For the chain growth an activation energy of Ep = 37 kJ/mol and an activiation volume of Δvp≠ = -25,5 ml/mol was found. The activiation parameters of the chain termination are Et = 9,9 kJ/mol and Δvt≠ = 7 ml/mol. Based on these results and literature data the rate constants of different chain transfer reactions involved in the high pressure polymerization of ethylene and their dependency on temperature and pressure were evaluated.
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    Functional metal-porphyrazine derivatives and their polymers, 7Part 6: cf.8.. Synthesis and properties of metal-2,9,16,23-tetracarboxyphthalocyanine covalently bound to poly(2- or 4-vinylpyridine-co-styrene) (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 691-699 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Metal-2,9,16,23-tetracarboxyphthalocyanines(Mt-taPc's) [Mt = Fe(III), Co(II), Ni(II), Cu(II)] covalently bound to poly(2- or 4-vinylpyridine-co-styrene) were synthesized by Friedel-Crafts reaction of the styrene units of the copolymers with Mt-taPc tetraacid chloride. The copolymers contain about 0,3 to 14,6 mol-% Mt-Pc rings and are soluble in methanol, ethanol, and N,N-dimethylformamide. The coordination spheres around the Mt-Pc rings were characterized by electronic as well as ESR spectra and by viscosity measurements. The dimerization of Mt-taPc in the copolymers is sterically hindered by the polymer chain. The copolymer supported Fe(III)- or Co(II)-taPc's are of the five coordinate high spin type in DMF solution. One coordination site at axial position of the Mt-Pc ring may be occupied by an N atom of a pyridine group. The electronic structures of the metal atoms may be useful in catalytic reactions.
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    Syntheses and characterization of polycondensation products derived from β-(4-methoxy-3-methyl)phenylglutaconic acid and diols (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 733-735 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Five new copolyesters 3a - e were prepared by reacting β-(4-methoxy-3 methyl)phenylglutaconic acid dichloride (1 b) with diols 2 a - e. The polymers were characterized by IR and TG. All polymers were found to decompose in the range of ≈200 to ≈650°C.
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    Reactive microgels by the self-emulsifying copolymerization of unsaturated polyester resins with acrylic and methacrylic esters (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 755-762 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The self-emulsifying copolymerization of unsaturated polyesters (UP) with various acrylic and methacrylic esters was studied. The structure of comonomers significantly influences the character of microgels obtained. Among these monomers the copolymerization of UP with methyl methacrylate (MMA) was investigated in detail in order to make clear the behavior of this polymerization as compared with that of styrene. The water/monomer and UP/MMA ratios were found to be the most important factors controlling the molecular weight and solution viscosity of the microgels. The relationship between M̄w and intrinsic viscosity of microgels suggests that the microgels from MMA have less compact structure than those from styrene.
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    Pharmacologically active polymers, 23Part 22, cf.: T. Hirano, H. Ringsdorf, D. S. Zaharko, Cancer Res. 40, 2263 (1980).. Linear and branched zwitterionic derivatives of polyethyleneimine as carriers for pharmacologically active components (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 793-801 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: To obtain a carrier polymer for pharmacologically active components, linear polyethyleneimine (LPEI) was chemically modified by reactions with acrylic acid (1a), acrylamide (1b), acrylic acid esters (1c and 1d), sodium chloroacetate, and hydrochloric acid. All product polymers 2a - 2e are soluble in water. Among these, 2a and 2e, β- and α-amino acid derivatives, respectively, show no acute toxicity in mice up to dosages of 1 g/kg i. v. Similar types of polymers 5a and 5b and a polymer containing phosphonic acid moieties (5d) derived from branched polyethyleneimine (BPEI) were prepared. 5a and 5b are also nontoxic regardless of the molecular weight of four kinds of BPEI and of the wide range of carboxylic group content in the polymer. It is suggested that the zwitterion form contributes to the nontoxic nature of β-and α-amino acid type polymers. The present results show that amino acid type polymers derived from LPEI and BPEI can be used as carrier polymers for pharmacologically active components.
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    Promotion of charge-transfer complex formation by β- or γ-cyclodextrin (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 837-847 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The formation of charge-transfer (CT) complexes between eleven naphthalene derivatives and eight di- or trinitrobenzene derivatives in water and in water-organic solvent systems has been studied in the presence and absence of β- or γ-cyclodextrin (β- or γ-CDx), respectively. Data of UV absorption and circular dichroism (CD) clearly revealed that γ-CDx, in several cases, assists CT complex formation by accommodating both electron donor (D) and acceptor (A) molecules in its cavity simultaneously. Thus the weak CT band was intensified and even some systems in which CT complex formation was usually not observed produced CT complexes by the addition of γ-CDx. In contrast, β-CDx did not promote markedly the CT complex formation except in one case. It did promote the CT complex formation between α-naphthylacetic acid (α-NAA) and picric acid (PA), manifesting the capability of β-CDx to include two aromatic molecules. Magnetic circular dichroism (MCD) associated with the CT bands was detected for a π - π* type CT complex for the first time, but its intensity was quite weak as anticipated from theory.
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    Asymmetric selective oligomerization of chloromethyloxirane (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 895-906 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Chloromethyloxirane (CMO) undergoes an asymmetric selective oligomerization with a binary catalyst system comprised of triethylaluminium and an optically active cobalt complex, N,N'-disalicylidene-(1 R)-1,2-cyclohexanediyldiaminatocobalt(II). A series of optically active oligomers obtained were isolated and characterized. Two kinds of linear oligomers were produced with respect to the end groups, namely epoxy- and halohydrin-ended oligomers. A mechanism for the selective formation of linear oligomers by the present catalyst system is proposed.
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    Electron transfer process in the microdomains of poly(sodium styrenesulfonate)-poly(alkylene viologen) complexes (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1061-1070 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The electron transfer process in the microdomain of a polyion complex composed of poly(sodium styrenesulfonate), (syst. name: poly[sodium 1-(4-sulfonatophenyl)ethylene]), and poly(alkylene viologen)s 1 with 3 to 10 methylene groups between two adjacent viologen units was analyzed by means of voltammetry with a rotating disc electrode. Although the stability of 1 on the graphite electrode was improved by the formation of a polyion complex with poly(sodium styrenesulfonate), a smaller surface charge was observed in the polyion complex as compared with the electrode coated with poly(alkylene viologen) alone. Since the migration of the counter ion was clarified to be indispensable for the electron transfer in this case, the microdomain of polyion complexes should be formed by tightly-shrunk polyelectrolyte chains. Furthermore, the electron transfer in the microdomain of the polyion complex is hardly detected, when the electrode is coated with an excess of the complex. The electron transfer strongly depended on the average distance between two adjacent redox sites in the matrix. These matrixes were suggested to be controlled by the subtle balance of hydrophobicity and charge density of 1.
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    New experiments concerning the mechanism of solid-state photopolymerization of 2,5-distyrylpyrazineDedicated to Prof. Dr. H.-J. Cantow on the occasion of his 60th birthday, with warmest personal wishes (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1103-1119 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photoinduced formation of oligomers in single crystals of 2,5-distyrylpyrazine (DSP) was investigated by X-ray and electron diffraction techniques and also by gel permeation chromatography (GPC). The DSP crystals were characterized for the presence and nature of dislocations by dark-field images and etch-pit studies. Small angle grain boundaries were identified to be the prominent feature, but in general the crystals were highly perfect. A correlation between the sites of the defects and the formation of the photoproduct could not be detected. The oligomers formed in a solid-solution under appropriate irradiation conditions. Thus, DSP oligomer of number average degree of polymerization P̄n = 3,2 in macroscopic single crystal texture was obtained for the first time using a laser light source at 478 nm. Deterioration of the single crystal texture of DSP usually observed during photopolymerization is explained as being caused by inhomogeneous light distribution which in turn causes an inhomogeneous product distribution with accumulation of large strain fields. These can be made visible by the multiplication of etch pits. Phase separation between oligomer and polymer is observed on further irradiation of the oligomer single crystals. The oligomer phase seems to play the role of an intermediate in the photopolymerization of DSP at wavelengths λ 〈 400 nm. The molecular weight distribution of the oligomers was studied by GPC. The data are only compatible with the assumption that the rate constant of dimerization is higher than that for the addition of a monomer to an already existing oligomer.
    Additional Material: 13 Ill.
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    Functional monomers and polymers, 105Part 104: Y. Sakuma, Y. Inaki, K. Takemoto, J. Polym. Sci., Polym. Chem. Ed., in press.. Synthesis of poly(β-alanine) from a new type of active amino acid ester (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1171-1178 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Active β-alanine esters having dipeptide groups, which are capable of forming hydrogen bonds between the side chains, were prepared in the form of hydrogen chloride salts. The polycondensation of these salts was studied in non-polar solvents, in the presence of triethylamine. In the case of the ester with β-alanyl-β-alanine as dipeptide moiety, the polycondensation proceeded smoothly in chloroform solution. To explain the characteristic feature of the polycondensation, an ordered aggregation of the ester molecules is assumed to play an important role. The ester with glycylglycine as dipeptide moiety, however, did not undergo a polycondensation.
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    Conformational analysis of polyoxyethylene using empirical force field methods (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1285-1293 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Conformanational energies of various oligo (oxyethylene) isomers were calculated by the empirical force field method, and statistical mechanics calculations of the chain dimensions and the dipole moments were carried out. The results are seriously different from those obtained for poly (oxymethylene). Although the first-order steric interactions in POE are of the same order of magnitude as those in n-alkane chains, the second-order interactions are significantly different. The second-order interactions arising from rotations around two consecutive bonds of OCH2CH2OCH2 in g± g∓ conformation have greatly reduced steric repulsions. It was found that the reduced second-order interaction plays an important role in the configurationdependent properties of POE. The agreement of the calculated values for the unperturbed dimensions and the temperature coefficients obtained from the force field method with experimentally observed ones is fairly good.
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    Role of cocatalysts in polymerizations initiated with benzyl derivatives of transition metals, 1. Polymerization of ethylene (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1389-1395 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of ethylene initiated in naphta solution by Zr(CH2C6H5)4 at 200°C under high purity conditions showed a cocatalytic effect of water with a maximum rate for a mole ratio H2O/Zr close to 0,1. No activity was observed for the hypothetical compound (C6H5CH2)3ZrOZr(CH2C6H5)3. Ethylene polymerization was also initiated with supported catalysts obtained by reaction of Zr(CH2C6H5)4 with silicium oxide or pre-dried aluminium oxide with an increase of activity (by a factor of 5). The resulting polyethylenes were found to be virtually linear with 1,5 CH3 groups for 1000 C atoms and with melting points of 134 - 136,5°C. They have high molecular weights with very broad distribution. These results were interpreted by a mechanism involving Ziegler-like active centers.
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    Chemische synthese verzweigter polysaccharide, 109. Mitteilung: cf.6.. Polymere mit amidartig gebundenen mono- und oligosaccharid-seitenkettenHerrn Professor Dr. H.-J. Cantow zum 60. Geburtstag gewidmet (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1441-1458 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Binding of mono-, di-, and oligosaccharides by amide linkage to polymers carrying carboxylic or amino groups was studied with synthetic polymers (poly(acrylic acid), poly(vinylamine)) and polysaccharide derivatives (e.g. chitosan). Suitable methods are described which allow a variation of the number and lenght of the attached saccharide branches. In the absence of salt, all products with a degree of substitution (DS) 〈 1 show polyelectrolyte behaviour. Compared with the unsubstituted polyelectrolytes, for the branched polymers a substantial increase of the viscosity was observed within a certain range of branch density. In the case of glucose side chains, the maximum viscosity was found near DS = 0,1. In the case of maltose side chains, this maximum of the viscosity occurred at higher DS. A similar but smaller increase in the viscosity was observed in 0,1 M NaCl solution. The results are explained by a shielding of the backbone charges from the counterions and by an additional chain stiffening effect resulting from hydrogen bonds, i.e., ring formation between the amide linkage and adjacent free carboxylic or amino groups.
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    Properties of liquid crystalline polymers in solution, 1. Determination of the molecular weight of polymethacrylates with mesogenic sidegroupsDedicated to Professor Dr. H.-J. Cantow on his 60th birthday (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1489-1496 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Derivatives of poly(methacrylic acid) with mesogenic sidegroups are aggregated in solution. Through structural changes which also take place in the solid state, the fraction of the aggregates increases with storage time. The formation of aggregates depends on temperature and occurs relatively slowly. In solution, the degree of aggregation strongly depends on the solvent. This aggregation leads to relatively high tacticity in products obtained by radical initiated polymerisations.
    Additional Material: 6 Ill.
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    Orientierungsverhalten von segmentierten polyetherurethanen in abhängigkeit von der dehnung und den verwendeten lösungsmittelnHerrn Prof. Dr. Cantow zum 60. Geburtstag gewidmet (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1529-1546 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solvent influence on two- phase structures resulting from drying films of segmented polyetherurethanes of different hard segment contents and molecular weights was investigated by infrared dichroism measurements of the orientational behaviour of the hard segments. A low density of physical crosslinking and/or minor association in solution leads to a lamellae structure resulting in an inhomogeneous distribution of stress at elongation. The formation of lamellae is impeded, if the solution shows pronounced formation of associates. Destruction of the lamellae can be monitored by studying the orientational behaviour for repeated deformations and by means of orientation-extension-hysteresis experiments. Stress-strain diagrams exhibit no contradictions to the discussed structural transformations by the influence of different solvents.
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    High conversion copolymerization, 2Part 1: cf.8.. Styrene/maleic anhydride copolymer composition studies (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1597-1602 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The free radical initiated copolymerization of styrene with maleic anhydride at high conversions is studied. The data of the fractional conversion of the comonomers, of the fractional copolymerization rate, of the instantaneous and cumulative composition of the copolymer for the copolymerization of an equimolar mixture of styrene and maleic anhydride in ethyl methyl ketone (at 60°C) and in 1,4-dioxane (at 120°C) up to high conversions as a function of the reaction time (resp. conversion) are presented. Negligible differences at 60°C, but significant ones at 120°C were found between the experimentally measured fractional compositions and those calculated according to the integrated form of the copolymer composition equation (Mayo-Lewis equation), using the published values for the copolymerization reactivity ratios.
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    A correlation of anodic peak potentials with HOMO energies of various monomers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1661-1667 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electroinitiated cationic polymerization of olefins can be initiated by direct electron transfer from the highest occupied molecular orbital (HOMO) of monomers, by constant potential electrolysis. Potentials, at which some monomers lose electrons, were measured by cyclic voltammetry. Measurements were made on a Pt electrode versus Ag0/Ag+, in acetonitrile. The measured anodic peak potentials (Ep,a) were correlated to HOMO energies (∊m), calculated by Hückel molecular orbital (HMO) considerations for coplanar molecules. For methyl-substituted monomers the ω-technique was also applied. A linear equation has been developed for Ep,a as a function of ∊m, for styrene derivatives having +I and +E substituents.
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    Lyotropic and thermotropic liquid-crystalline phase formation from fractions of a semiflexible cellulosic polymer (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1727-1740 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The benzoic acid ester of (2-hydroxypropyl)cellulose (BzPC) was prepared and fractionated from acetone solution by precipitation with methanol-water (85:15, by volume). The fractions were characterized by low-angle laser light scattering in tetrahydrofuran, and by size exclusion chromatography with a low-angle laser light scattering detector. Dilute solution viscosities were measured in acetone and benzene, and the results were interpreted on the basis of a worm-like chain model for BzPC. The critical concentrations of polymer necessary to form lyotropic cholesteric phases in acetone and benzene were found to decrease as the molar mass of the polymer increased, reaching a limiting volume fraction of ≈ 0,35 for high molar mass fractions. The experimental results were compared with the prediction of recent theories for the formation of liquid crystalline phases from semiflexible polymers; the chain parameters required by the theories were estimated from dilute solution viscosities. The fractions of BzPC also showed a thermotropic transition from liquid crystalline phase to isotropic melt. The transition temperature increased sharply with increasing molar mass to reach a limiting value of 176°C.
    Additional Material: 7 Ill.
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    Functional monomers and polymers, 109Part 108: Y. Suda, Y. Inaki, K. Takemoto, J. Polym. Sci., Polym. Chem. Ed., in press.. Asymmetric inclusion polymerization of (E)- and (Z)-2-methyl-1,3-pentadiene in apocholic acid canalsDedicated to Professor H. J. Cantow on the occasion of his 60th birthday (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1771-1779 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Asymmetric inclusion polymerization of the prochiral monomers (E)- and (Z)-2-methyl-1,3-pentadiene (3a and 3b), in apocholic acid (2) canals was performed under various conditions to find out the factors controlling the asymmetric induction during the polymerization. Ozonolysis of the resulting polymers and subsequent transformation of the resulting 2-methyl-4-oxovaleric acid (4) into its 2,4-dinitrophenylhydrazone revealed the predominant formation of the (R)-absolute configuration. The optical yield was high in the initial stage of the polymerization and decreased gradually as the polymerization proceeds. To obtain a high optical yield the polymerization was performed at low temperature applying a 1:1 mole ratio monomer/apocholic acid, and an irradiation dose 〈 1 Mrad. The optical yield amounted to 36% at maximum, which is the highest value obtained so far in the asymmetric polymerization of 1,3-pentadiene derivatives using canal complexes or other known methods.
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    29Si NMR-untersuchungen an polykieselsäureestern (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1817-1822 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Linear and branched siloxanes were prepared by partial hydrolysis of silicon tetrachloride and by esterification of the products of hydrolysation with methyl and ethyl nitrite. 29Si NMR spectra made it possible to distinguish between the isomers of each oligomer up to the heptamer. Linear relationships between the 29Si chemical shifts of the ethyl and the methyl esters on one hand and between the ethyl esters and the poly(silicic acid)s on the other hand were observed. However, due to the different effect of neighboring building units, there are only poor relationships between the 29Si data of the esters and the chloro derivatives.
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    Radical polymerization of methyl methacrylate initiated by the liquid crystalline compound cholesteryl oleyl carbonate (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1555-1560 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) at 30, 55, 65, 75, and 85°C in the presence of the cholesteryl liquid crystal compound cholesteryl oleyl carbonate (CHOC) are reported. The conversion increases, whereas the molecular weight remains constant, with increase in concentration of CHOC in the range 0,2 to 0,6 mol-%. The activation energy for the polymerization of MMA was found to be 66,3 kJ/mol. The polymerization is inhibited in the presence of the radical scavengers 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroquinone. VAc does not polymerize in the presence of CHOC for 20 h at 65°C. The interaction between MMA and CHOC is investigated by viscometry of toluene solutions and by UV spectrophotometry of CCl4 solutions. The equilibrium constants and the molar absorption coefficients for a 1:1 complex for MMA-CHOC and for a 2:1 complex for VAc-CHOC are reported. A plausible mechanism for the spontaneous polymerization of MMA in the presence of CHOC is presented. The tacticities of the polymers formed in the presence of CHOC are discussed.
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    Polymerization of aromatic methacrylates to high degrees of conversion (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1571-1576 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerizations of 2,4,6-tribromophenyl methacrylate (1a), p-tolyl methacrylate (1b), p-cyclohexylphenyl methacrylate (1c), and p-methoxyphenyl methacrylate (1d) were carried out up to conversions higher than 99%. The kinetics of the process was followed by the refractometric technique using a He-Ne laser as light source. The influence of the concentration of initiator on the appearing of the gel effect was examined, taking the polymerization of 1a as an example.
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    Influence of the structure of chlorophenyl 2,3-epoxypropyl ethers on their reactivity in ionic polymerization (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1577-1584 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Empirical correlation equations could be derived for comparison of the relative reactivities of a homologous series of chlorophenyl 2,3-epoxypropyl ethers in cationic polymerization initiated by SnCl4, and in anionic polymerization initiated by KOH. These equations include a conformation constant, Sk, accounting for the interaction between the oxirane ring and the aromatic substituent. For the anionic polymerization the saponification number must be introduced additionally into the correlation equation to account for a side reaction between initiator and substituent.
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    Parameters of the generalized exponential function for the molar mass distribution of the polystyrene standard NBS 706 (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1653-1659 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The experimental molar mass distribution of the polystyrene standard NBS 706, as determined by high performance size exclusion chromatography, has been fitted with the generalized exponential function, whose parameters have been evaluated by a computer procedure. Comparison is made with the Schulz-Zimm and logarithmic normal distributions, and the consistency of the different average molar masses is discussed.
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    Comparison of methods for determination of the number of active centers in Ziegler-Natta polymerizationsDedicated to Professor Ing. Dr. O. Wichterle on the occasion of his 70th birthday (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 1975-1985 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Four intrinsically different methods for the determination of the number of active centers were employed in propylene polymerization catalyzed by the typical heterogeneous system TiCl3/AlEt2Cl: (i) determination of M̄n (GPC method) and calculation of number of macromolecules therefrom; (ii) quenching with BuOT and determination of tritium in the polymer; (iii) quenching with CO or CO2 and determination of carbonyl groups in the polymer (IR spectroscopy); (iv) quenching with SO2 and determination of sulfur in the polymer. The first two methods exhibited a reasonable agreement for the number of active centers. Method (iii) gave much lower values, whereas method (iv) was found to be virtually unsuitable due to a high extent of side reactions of SO2 with the polymer. A similar comparison of the methods was made in ethylene polymerization catalyzed by the typical homogeneous systems Cp2TiEtCl/AlEtCl2 and Cp2TiEtCl/alumoxane. Method (ii) gave a much lower number of active centers than method (i), due perhaps to a low extent of alcoholysis of the Ti—C bond or to a high kinetic isotope effect. CO2 appeared to be entirely inert as a quenching agent and CO had been reported to show side reactions. It follows that none of the above quenching methods have universal application and thus literature data should be considered with caution.
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    Vinyl polymers with aromatic substituents, 2Part 1: cf.2. Polymerization of 9-allylanthracene and structures of the polymers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2033-2040 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Radical, cationic, and Ziegler-Natta polymerizations of 9-allylanthracene (1) were carried out. The radical polymerization was found to be an inefficient method leading to oligomers with complex structure. Reaction of initiator radicals and growing macroradicals with the anthryl group or with the allylic hydrogen leads to resonance stabilized radicals which stop the polymerization. The cationic and Ziegler-Natta polymerizations gave a copolymer with 9-anthrylmethylethylene units (8) (from normal 1,2 addition) and 9,10-anthrylenepropylene units (11) (from the electrophilic attack of carbocations at the aromatic nucleus). Low polymerization temperatures lead to a preference for the alkylation reaction.
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    Metalloester, 109. Mitteilung: cf.1. Die in den Veröffentlichungen Metalloester 9 and 10 enthaltenen Ergebnisse wurden auf dem V. Internationalen Mikrosymposium über «Fortschritte in den Ionenpolymerisationen» in Prag, im Juni 1982, vorgetragen. Untersuchung des anfangsstadiums der anionischen polymerisation von methylmethacrylat. einfluß von reaktionsbedingungen auf die umsetzung von methyl-2-sodioisobutyrat mit methylmethacrylatProf. Dr. Otto Wichterle zu seinem 70. Geburtstag gewidmet (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2021-2031 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In continuation of a preceding study, the course of the reaction between methyl methacrylate (2) and methyl 2-sodioisobutyrate (1) was investigated, applying reaction times between 0,02 and 1,4 s, as a function of the following conditions: character of the solvent, effect of the addition of sodium tert-butoxide, mole ratio 2/1, concentration of the reactants, and temperature. Under all conditions used, the reaction between 2 and 1 was very fast and gave rise, along with other compounds, to a mixture of oligomers of 2 with the average molecular weight obeying the ratio [2]:[1]eff.. The balance of products showed that in some cases only a part of 1 has reacted with 2, giving rise to the expected oligomers. The efficiency of 1 varied in the range from 24 to 100%, being mainly dependent on the character of the solvent (efficiency in THF 〉 in toluene). Moreover, it was higher in the presence of sodium tert-butoxide and with a higher 2/1 mole ratio. In experiments with a low efficiency of 1 a certain part of it remained unreacted, in spite of the presence of 2, for reasons not yet clear. The resulting oligomers undergo consecutive reactions. Starting with the trimer 3b, cyclizing selfcondensation was the most important of the consecutive reactions and could be easily investigated in the case of the trimer. The rate of this cyclization was much higher in THF than in other solvents used, and it was, therefore, difficult to obtain the linear trimer at room temperature. On the contrary, the addition of sodium tert-butoxide or lowering the temperature suppressed the cyclization, which was especially easy to perceive in THF. Using the experience described in the study, it is possible to choose such conditions of the reaction between 1 and 2, under which the required oligomers are formed in good yield.
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    Hydrodynamic crossover in two-polymer mixtures from viscosity measurements (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2153-2158 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A very sharp crossover is observed in the variation of the reduced viscosity ηsp/c as a function of the concentration c for mixtures of 1:1 by weight mixtures of polystyrene and poly(methylmethacrylate) in benzene at 20°C and a 1:1 by weight mixture of poly(ethylene glycol) and polystyrene in benzene at 20°C. The crossover is attributed to the critical to the concentration of the two respective polymers in the solution and its sharpness is due to the incompatibility between the two different polymers.
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    URL: http://dx.doi.org/10.1002/macp.1983.021841019
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    Preliminary results on ethylene/propene copolymerization in the presence of Cp2Ti(CH3)2/Al(CH3)3/H2O (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2193-2198 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethylene/propene copolymerizations were carried out in the presence of the catalyst system Cp2Ti(CH3)2/Al(CH3)3/H2O (Cp = cyclopentadienyl group), and the reactivity ratios r1, r2 were determined through the Fineman and Ross equation and via 13C NMR. A nearly alternating copolymer structure was pointed out. The yields as well as the molecular weights of the copolymers strongly decrease with increasing propene mole fraction in the copolymers.
    Additional Material: 2 Ill.
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    Lichtinitiierte polymer- und polymerisationsreaktionen, 10Teil 9: cf.21.. Photoinduzierte zersetzung von diareniodonium- und triarensulfoniumsalzen durch kaliumtrisoxalatoferrat (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2409-2419 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In order to elucidate kinetics and mechanism of photoinitiation processes based on potassium trioxalatoferrate(III) (K3[Fe(cx)3])/ onium compounds/acrylamide (AA) interactions, photolysis and stationary photopolymerization were carried out. Diphenyliodonium chloride (Ph2I⊕Cl⊖) and triphenylsulfonium tetrafluoroborate (Ph3S⊕BF⊖4) were used as onium compounds. These compunds react with photolytically formed ·CO⊖2 radicals by an electron transfer mechanism. The resulting phenyl radicals were detected by spin trapping with nitrosodurene. The quantum yield of the decomposition of onium salts, φIn, depends both on their reduction potentials and concentrations. Thus, an efficient redox reaction between ·CO⊖2 radical and Ph3S⊕BF⊖4 is impossible because the former reacts faster with the Fe(III) complex. The ratio between rate constants of these competitive reactions (onium compound/Fe(III)) are 0,1 (Ph2I⊕Cl⊖) and 4 · 10-4 (Ph3S⊕BF⊖4). Only with the system K3[Fe(ox)3]/Ph2I⊕Cl⊖/AA a radically induced photopolymerization was observed. Both the rate and the quantum yield (φBr) depend on the Ph2I⊕Cl⊖ concentration. A correlation between φBr and √φIn was found.
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    Synthesis and characterization of some new polyamides containing azomethine groups in the polymer backbone, 2Part 1: cf.7. (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2447-2455 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New aromatic polyamides containing azomethine groups in the backbone and also having different linking groups like —CH2—, —CH2—CH2—, and —O— were synthesized by reacting 4,4′-[1,4-phenylenebis(methylidynenitrilo)]dibenzoyl dichloride (2) with some diamines 1a - d, 4, and 6 by the low temperature solution polycondensation method. The physical, spectral, and thermal properties of the synthesized polyamides were investigated. The effect of the nature of different linking groups on the properties of these aromatic polymides was explored by comparing their spectral and thermal data.
    Additional Material: 6 Ill.
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    Aqueous gel permeation chromatography of electrolytes and polyelectrolytes, 2Part 1: cf. 10.. Donnan salt exclusion effectDedicated to Professor Dr. H.-J. Cantow on his 60th birthday (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2593-2601 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The salt exclusion of electrolytes and polyelectrolytes in aqueous GPC was investigated theoretically and experimentally, in order to elucidate the feasibility of GPC as a technique for measuring the Donnan salt exclusion parameter, Γ¯, of polyelectrolytes. Three simple salts different in the valency of the anion, i.e., sodium chloride, sodium sulfate and naphthalene-1,3,6-trisulfonic acid trisodium salt, were eluted with aqueous NaNO3 solution on a Sephadex G-10 gel column. The experimental results were analyzed in terms of the Donnan equilibrium established on the gel, and the Γ¯ value of these simple salts was evaluated. It was found that the Γ¯ value from GPC was in good agreement with the theoretical value of 1/2 for an ideal case, showing that the colligative properties of electrolytes and polyelectrolytes such as Γ¯ can be accurately investigated by means of GPC. GPC experiments on the Donnan salt exclusion were further carried out for the heparin-NaCl system by using a Sephadex G-25 gel column. From the experimental data, the Γ¯ value of heparin was estimated.
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    IR-bandenstrukturanalyse der amidstreckschwingungen von N-methylacetamid als modellsubstanz für makromoleküle mit peptidbindungen (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 2693-2704 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The C=0 and N—H stretching vibrations of N-methylacetamide in solution were studied at different concentrations and temperatures. By means of bandfitting and using the second derivative, the C=O stretching band (Amide I) was resolved into four component bands. An assignment of these frequencies is discussed. The band splitting of amide I indicates the presence of cis-trans isomerism about the peptide (—CO—NH—) link and a frequency shift of the free C=O end groups of associated molecules. The H-bond enthalpy seems to be influenced by the chain length of the associates.
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    Degradation and depolymerization of poly(propylene carbonate) by diethylzinc (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 907-912 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Poly(propylene carbonate) (PPC) was treated with diethylzinc in 1,4-dioxane solution at 30°C, Zn(C2H5)2 being used in excess or defficiency with regard to carbonate units. PPC was found to undergo degradation and depolymerization reactions, which were followed via the polymer intrinsic viscosity and the propylene carbonate yield. A model reaction between diethyl carbonate and diethylzinc was carried out too. From the results, a mechanistic view for both pathways, degradation and depolymerization, is proposed.
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    Immobilisation du complexe de nickel de l'histidine L(+) sur des supports macromoléculaires hydrophiles (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 9-16 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: N-(4-vinylbenzyl)-L-histidine (5) and the corresponding methyl ester were synthesized by reacting L-histidine or L-histidine methyl ester with 4-formylstyrene. N-(4-vinylbenzyl)-L-histidine methyl ester was radically copolymerized with various amounts of 2-hydroxyethyl methacrylate and ethylene dimethacrylate, leading to resins of different degrees of hydrophilicity and crosslinking. After saponification of the histidine ester groups, the resins were chelated with Ni2+ salt in order to be used as polymeric catalysts in enantioselective ester hydrolysis reactions.
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    Hydrolyse énantiosélective d'α-aminoesters catalysée par des complexes chiraux de métaux de transition immobilisés sur supports macromoléculaires (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 17-28 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The kinetics of hydrolysis of D- and L-histidine methyl ester were studied in the presence of crosslinked hydrophilic polymeric supports bearing L-histidine moieties complexed with Ni2+ salt. The selectivity of hydrolysis (kD/kL ratio) rises with the increase of the hydrophilic character (content of monomeric units of 2-hydroxyethyl methacrylate) of the resin. It varies with the ratio ester / catalytic moiety, the best result being obtained when the latter is close to 1. The selectivity depends on the temperature and an inversion of this selectivity is observed at 31°C. The optimization of all the parameters studied allowed to reach the same enantioselectivity and comparable rates of hydrolysis as observed in a model reaction carried out under homogeneous conditions.
    Additional Material: 7 Tab.
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    Hochdruck-hochtemperatur-reaktionen in einem strömungsreaktor, 1211. Mitteilung: cf.1. Thermische dimerisierung von acrylsäauremethylester, methylvinylketon und acrylnitril (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 63-69 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Thermal dimerization of methyl acrylate to dimethyl 2-methyleneglutarate was performed in a high pressure-high temperature flow apparatus at temperatures up to 420°C and pressures up to 200 bar. The head to head dimer dimethyl 2-methyl-3-methylenesuccinate was observed, too. Methyl vinyl ketone and acrylonitrile are able to dimerize analogously.
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    A statistical analysis for stereo-configurational sequences of vinyl polymers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 91-104 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: In this paper, the distribution of configurational sequences in vinyl polymers is re-treated theoretically by the aid of statistics. Various Markovian probabilities of multi-ads are listed. A series of relationships among the frequencies of occurrence of n-ads with different configurations is obtained, most of them have not been reported up to now. Finally, a convenient method for determination of the order of a Markovian process is established.
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    Etude de la structure ramifiée du polyéthylène basse densité par viscosité et diffusion de la lumière de fractions issues de la chromatographie d'exclusion gpc (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 135-145 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Fractions of high density polyethylene (PEhd) and low density polyethylene (PEld) obtained from gel permeation chromatography were studied by viscometry and light scattering. The variations of the intrinsic viscosity [η], the molecular weight M̄w, and the radius of gyration Rg for PEhd and PEld were compared with one another and the relationships [η] vs M and Rg vs. M for PEhd were established. The dependence of structural parameters g = (Rg2)branch/(Rg2)linear and g′ = [η]branch/[η]linear on the molecular weight was determined for three samples of PEld.
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    On the principle of equal reactivity in solution polycondensation (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 105-111 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of the degree of polymerization of oligomers (1 ≤ l ≤ 50) on the reactivity of the OH endgroups is exemplified by the reaction of oligoterephthalates of phenolphthalein with benzoyl chloride under ϑ-conditions. It is found that with increasing chain length l the hydroxyl group activity increases according to an S-form law. It is suggested that the ester groups of the macromolecule influence the activity of the OH endgroups due to solvation effects. This suggestion is confirmed theoretically and experimentally.
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    The stochastic kinetics of intramolecular reactions in linear polymers (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 123-134 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper deals with the kinetics of reactions of linear flexible macromolecules in solution possessing initially several reactive sites per macromolecule. It is assumed that the reactive sites interact with each other encounter-controlled and that both intra- and intermolecular reactions are possible. On the basis of the theory of stochastic kinetics in microsystems, equations were derived, describing the kinetics of intramolecular reactions as a function of the molecular weight distribution. An important application of this theoretical treatment pertains to the distribution between inter- and intramolecular reactions. A demonstration for typical reaction conditions reveals the influence of rate parameters and of the average number of reactive sites per macromolecule r̄(0) on the proportionate distribution expressed by fA = f (r̄(0)); (fA = fraction of intramolecular reactions). This function is only weakly influenced by varying the width parameter β in the case of Schulz-Zimm molecular weight distributions from β = 1 to → ∞.
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    Crystallization of polydisperse polyethylene fractionated according to pennings' method (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 225-232 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: It is shown that the molten state and the semi-crystalline state of polydisperse polyethylene are interrelated. Large polydisperse fractions obtained according to Pennings' fractionation method were studied by small angle X-ray scattering and differential thermal analysis; the long period, depending on the molecular weight distribution, is shown to be given by the weight average end-to-end distance of the coils; the long chains with molecular weights M 〉 105 behave as a series of “sub-chains” with molecular weight M* = 105 which crystallize independently. The same result is found for fractions with narrow molecular weight distribution and for mixtures of polyethylene fractions.
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    Fixation sur cellulose de médicaments libérables par voie enzymatique (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 277-285 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As an approach to the programmed release of drugs a polymeric carrier (1) from which the drug would be liberated by the degradation of definite covalent chemical bonds by means of specific enzymes, was synthesized by coupling pholcodine (2), an antitussive drug, with an insoluble, physiologically inert polymer, cellulose, using L-phenylalanine as a spacer arm. As chemical bond between drug and amino acid an ester function was chosen linking the hydroxyl group of 2 and the carboxylic end of L-phenylalanine. This linkage is not hydrolyzed in simulated digestive fluids containing pepsin or trypsin; it is only broken in the presence of α-chymotrypsin to release slowly the parent drug.
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    Polymerisationsauslösung mit substituierten ethanen, 54. Mitt. cf. 4.. Polymerisation von verschiedenen methacrylmonomeren (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 287-294 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Methyl methacrylate, benzyl methacrylate, butyl methacrylate, and methacrylic acid can be polymerized by 1,1,2,2-tetraphenyl-1,2-diphenoxyethane and 1,1,2,2-tetraphenyl-1,2-dicyanoethane. In the first period of the polymerization with both initiators oligomers are formed which can initiate the polymerization of other vinyl monomers yielding block-copolymers besides the resp. homopolymers.
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    Absolute determination of molar masses of standard polystyrenes by means of sedimentation-diffusion measurements in cyclohexane (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 295-308 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Accurate measurements of the sedimentation coefficients at unit pressure and zero-concentration s00, the diffusion coefficients at zero concentration D0, and the intrinsic viscosities [η] were conducted at theta-conditions (cyclohexane, 34,5°C) on 11 polystryrene standard samples with narrow molar mass distribution. These samples with nominal mass-average molar masses (5 · 104 〈 Mw 〈 2 · 106 g · mol-1), provided by three manufacturers for the use as calibration standards, were the same as in the previous paper of this series summarizing our measurements in toluene. Logarithmic correlations between s00, D0 and [η] are linear with deviations lower than ± 3% and indicate good consistency of all three independent sets of measured quantities. The molar masses MsD as determined from s00 and D0 by means of the Svedberg equation are in very good accordance with those previously determined in toluene, but for most samples the MsD are lower than the nominal values Mw as given by the manufacturers. For some standards the deviations amount to 15-35% and cannot be explained by experimental errors or by the polydispersity of the samples. On the other hand, two pairs of standards exhibit the same values of s00, D0 and [η] in both solvents, although the nominal molar masses differ by 20%. These results lead to the conclusion that the experimentally determined MsD values are more reliable characteristics of the standard samples than the nominal Mw values and that the sedimentation-diffusion technique is a powerful, though laborious, tool for an absolute determination of the molar mass.
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    Induced optical activity in copolymers of (-)-p-(3-menthyl) acrylate with 4-vinylpyridine (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 233-233 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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    International conference “polymer photochemistry” (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 234-234 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Synthesis and investigation of the properties of cardo-copolyimides with different microstructure (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 235-252 
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    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolyimides, their microstructure being determined by the method of synthesis, were prepared by copolycondensation of 4,4′-oxydiphthalic anhydride (1a), 4,4′-carbonyldipthalic anhydride (1b), or 1,8:4,5-naphthalenetetracarboxylic anhydride with a mixture of two diamines, hexa-, octa-, or dodecamethylene diamine (5a, 6a, 7a) and cardo-diamines 9,9-bis(4′-aminophenyl)fluorene (3a) and 3,3-bis(4′-aminophenyl)phthalide (4) or two aromatic diamines, 4,4′-oxydianiline (9) and 2,2-bis(4-aminophenyl)hexafluoropropane (8), at various mole ratios of the comonomers. Blockcopolyimides with five-membered imide cycles were formed by catalytic imidization of the intermediate polymers prepared by addition of the solid dianhydride to a solution of the mixture of the two diamines, whereas the thermal cyclization of such polymers and the one-step high-temperature synthesis led to random copolyimides. The thermal and mechanical properties of the copolyimides with various microstructure and their solubility in organic solvents were compared.
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    Hydrodynamic constants and frictional properties of polystyrene in dilute solution (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 309-317 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Experimental data from hydrodynamic measurements on eleven standard polystyrene samples in a poor and a good solvent (cyclohexane at theta-temperature 34,5°C, toluene at 25°C) are analyzed in terms of the two-parameter theory of the hydrodynamic properties of random coils. The discussion is focussed on the expansion factors of hydrodynamic radii αf and αμ, evaluated from the translation friction coefficients and the intrinsic viscosity, and on the hydrodynamic-interaction parameters P and Φ. The expansion factors αf and αη are shown to assume nearly equal values (at 1,15 ≤αη ≤ 1,5). That implies that the dependences on coil expansion must be very similar for P and Φ1/3. The value of the P parameter in the unperturbed state (i.e. P0) is shown to be close to that recently calculated by Zimm and to be significantly higher than the results of previous theoretical calculations.
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    Redox initiators for cationic polymerization: The diaryliodonium Salt/Sn(II) redox couple (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 463-473 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Diaryliodonium salts undergo facile copper catalyzed reduction in the presence of Sn(II) compounds. Such redox couples can be employed for the in situ generation of active initiators for cationic vinyl and ring opening polymerizations. Two mechanisms are proposed for the reduction reaction to explain the stoichiometry of the reactants and nature of the products formed. The polymerizations of several representative cationically polymerizable monomers were studied.
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    Polymerization of isobutene by the inifer technique, 1. Low molecular weight products using 1,4-bis(1-chloro-1-methylethyl)benzene/BCl3 as initiator (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 553-562 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cationic polymerization of isobutene by the “inifer”-technique was studied. Preliminary experiments are described which suggest that useful polymer can be prepared only when BCl3 is rapidly added to the premixed monomer/inifer mixture and that such polymerizations do not go to completion. Some questions regarding the mechanism are discussed and remain open.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840310
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  • 98
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    Molmassenverteilung und lösungszustand von linearen polyethylenen, 1. Lichtstreuungs-, viskositäts- und GPC-messungen (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 585-596 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Light scattering, viscosity and GPC measurements were performed on a homologous series of linear polyethylenes with viscosity average molar masses in decahydronaphthalene at 135°C between 1,0 · 105 and 2,7 · 106 g · mol-1 and relatively broad molar mass distributions. 1,2,4-Trichlorobenzene, α-chloronaphthalene, decahydronaphthalene (decalin) and decane were used as solvents. In the case of linear polyethylene in decahydronaphthalene and decane relationships between intrinsic viscosity and weight average molar mass were established. The values of the weight average molar masses obtained by light scattering are considerably higher than those obtained by viscosity and GPC measurements. These discrepancies are explained by molecular aggregation of the polyethylene macromolecules.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840313
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  • 99
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    Functional monomers and polymers, 103Part 102: Y. Sakuma, Y. Inaki, K. Takemoto, J. Polym. Sci., Polym. Chem. Ed., in press.. Synthetic application of polystyrene-bound chloropyrimidine and chloropurine as dehydrating and desulfhydrating reagents (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 497-503 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly{1-[4-(4-chloro-2-oxo-1,2-dihydropyrimidin-1-ylmethyl)phenyl]-ethylene} (1b) was pre-pared by condensation of chloromethylated polystyrene and uracil and subsequent reaction with POCl3, and used as dehydrating and desulfhydrating reagent for the preparation of hydro-xamates, acid chlorides, nitriles, and lactones. Other types of polymeric reagents, poly{1-[4-(2,6-dichloro-4-pyrimidinylaminomethyl)phenyl]ethylene} (4) and poly{1-[4-(6-chloro-9(7)-puri-nylmethyl)phenyl]ethylene} (5) were prepared analogously. It was found that 1 b shows the highest activity in these syntheses as compared with the other polymeric reagents 4 and 5.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840304
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  • 100
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    Vinyl polymerization initiated with systems of dimethylaniline N-oxide and some chlorosilanes (1983)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 184 (1983), S. 519-526 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Binary systems of dimethylaniline N-oxide (DMAO) and some chlorosilanes were found to be effective initiators for vinyl polymerization. The initiating activity of the chlorosilanes decreases in the following order: SiCl4 〉 CH3SiCl3 〉 (CH3)SiCl2 〉 (CH3)3SiCl. The copolymerization of methyl methacrylate (MMA) with styrene, initiated with the system DMAO/SiCl4, propagates via a radical mechanism. The polymerization of MMA with the system DMAO/SiCl4 was investigated kinitically in acetonitrile. The overall activation energy of the polymerization was calculated to be 44,4 kJ/mol, an extremely low value. The initial poly-merization rate(Rp) is of 1st order in monomer concentration. Rp is proportional to the square root of the DMAO concentration, and slightly dependent on the SiCl4 concentration for high SiCl4 concentrations. This suggests that a complex is formed between DMAO and SiCl4. Spec-troscopic results on the system DMAO/SiCl4 also indicate the formation of a complex. A yellow crystalline compound was isolated from the reaction of DMAO with SiCl4 at room temperature in methylene chloride/diethyl ether (1:3, by vol.). The complex has a composition of four moles of DMAO and one mole of SiCl4. From these results and from spin trapping studies, a possible initiation mechanism is proposed for the polymerization initiated with the system DMAO/chlorosilane.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1983.021840306
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