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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 168 (1989), S. 205-216 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde die Dehydrofluorierung von Polyvinylidenfluorid (PVDF)-Pulvern und -Filmen durch verschiedene basische Lösungen untersucht. Speziell die Reaktivität von 1,8-Diazabicyclo[5.4.0]-7-undecen (DBU) in Ethanol, KOH in 2-Propanol und wäßriger NaOH-Lösung mit Tetrabutylammoniumbromid wurde mit Hilfe von Veränderungen der Absorptionsbanden von PVDF-Filmen im Infrarot-(IR) und Ultraviolett-sichtbaren Bereich (UV-VI) untersucht. Neben den durch DBU oder KOH bewirkten Eliminierungsreaktionen treten sicherlich auch Substitutionsreaktionen auf. Die elektrische Leitfähigkeit von dehydrofluorierten PVDF-Filmen nimmt durch Dotierung mit Iod merklich zu, und die Aktivierungsenergien der Leitung liegen zwischen 0,4 und 0,5 eV. Verstrecken eines dehydrofluorierten und mit Iod dotierten PVDF-Films führt zu einer Anisotropie der Leitfähigkeit.
    Notes: The dehydrofluorination of poly(vinylidene fluoride) (PVDF) powder and films was studied using several kinds of base solution. Especially the reactivity of 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) in ethanol, KOH in 2-propanol and aqueous NaOH solution with tetrabutylammonium bromide was investigated by the change in infrared (IR) and ultraviolet-visible (UV-VI) absorptions of PVDF films. The elimination reactions by DBU or KOH were considered to be accompanied by substitution reaction. The electrical conductivity of dehydrofluorinated PVDF films increased markedly by doping with iodine, and the activation energies of conduction were found to be between 0.4 and 0.5 eV. When a drawn PVDF film was dehydrofluorinated and doped with iodine, anisotropy in conductivity was observed.
    Additional Material: 5 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 923-931 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dialkyldiallylammonium salts 1a-c were prepared by quaternization of diallylamine with alkyl bromides and their polymerizability as oriented molecular assemblies in aqueous solution is discussed. Thin films of those ammonium salts on the glass wall were incubated by adding a phosphate buffer solution to yield giant spherical vesicles with diameters ranging from 10 to 100 μm. When large amounts of the ammonium salt were applied, it was necessary to add more than 5 mol-% of cholesterol in order to stabilize the resulting giant vesicles. By ultrasonication of the film-aqueous solution system, much smaller vesicles with diameters ranging from 0,03 to 0,2 μm were obtained. The stabilizing effect of cholesterol addition to the system of the small vesicles is similar to that observed for the giant vesicles. Under an inert atmosphere, the vesicles in aqueous solution were polymerized by ultraviolet irradiation. From the results of TEM and NMR spectroscopy, it was concluded that the molecules were polymerized in the vesicles without changing the profile of molecular assembly during an irradiation of 6 h. However, when the ammonium salts were dissolved homogeneously in degassed benzene, the ultraviolet irradiation polymerization did not proceed beyond a conversion of 5% under the same conditions.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microstructure of poly[polytetrahydrofuran-block-poly(sebacoyl chloride-alt-hexamethylenediamine)]s 1-4, containing polytetrahydrofuran (PTHF) blocks of various molecular weights, and their blood compatibility were studied. These multiblock copolymers were prepared by interfacial polycondensation. The characterization of these copolymers was carried out by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), dynamic mechanical measurements, wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and electron spectroscopy for chemical analysis (ESCA). The TEM observation revealed the formation of a spherulitic structure at the copolymer surfaces, which is closely related to the homopolymer, polyamide (PA) 610. The DSC and dynamic mechanical measurements indicate the presence of distinct phase separation between PTHF and PA 610 blocks, and of the PTHF block in the copolymer being partially crystallized. The WAXD and SAXS indicate the formation of microstructures composed of crystalline and amorphous phases in the copolymer. Moreover, ESCA measurements verify that the surface chemical composition of the copolymer is identical to their bulk composition. Blood compatibility of these copolymers was evaluated by estimating platelet adhesion on the copolymer surfaces. Platelet adhesion was found to be affected by the PA 610 crystallinity, including the size and distribution of the crystalline phase in the case of the copolymers in which the PTHF blocks are completely amorphous (M̄n = 980). On the contrary, platelet adhesion at the copolymers in which the PTHF blocks are partially crystallized (M̄n ≥ 1560) depends upon the crystallinity of both PA 610 and PTHF, including the balance of crystalline (PA 610 and PTHF) and amorphous (mainly PTHF) phases. This result suggests that the balance of the crystalline and amorphous phase distribution in the copolymer is the most determinative factor for suppressing platelet adhesion at the copolymer surface.
    Additional Material: 15 Ill.
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  • 4
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Surface composition and blood compatibility of a series of segmented polymers based on poly(propylene oxide) (PPO) and nylon 610 were investigated. Electron spectroscopy for chemical analysis (ESCA) measurements revealed that the chemical composition of PPO-segmented nylon 610 surface is regulated by nylon 610 crystallization, and the PPO enrichment effect on the air-facing surface was correlated with both the degree of crystallinity of nylon 610 and the nylon 610 crystallite thickness. Platelet adhesion was minimized for the copolymer having a long period of approximately 12 nm and a crystallite thickness of 6,5 nm. This copolymer surface had the same chemical composition as the bulk, indicating that the particular surface microstructure composed of crystalline and amorphous phases could be a determining factor for suppressing platelet adhesion.
    Additional Material: 11 Ill.
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A 9% cross-linked porous polystyrene resin (10-15 μm) incorporating poly(γ-methyl L-glutamate) (PMLG) was synthesized, and the grafted PMLG was then converted into poly(N5-benzyl-L-glutamine) (PBLGN). In this newly developed procedure, almost quantitative conversion of PMLG to PBLGN is achieved. The obtained adsorbent for liquid chromatography demonstrated a total optical resolution of (RS)-5-isopropylhydantion. Experimental evidence demonstrated that the degree of polymerization (DP) of the incorporated poly(α-amino acid) is a critical variable. At DP = 2, no resolution was accomplished, whereas At DP = 14 or 36, base line resolutions were achieved. Other fundamental factors, such as the concentration of the immobilized PBLGN, the column temperature and the eluent composition, which affect the resolution efficiency, were also evaluated.
    Additional Material: 7 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymer adsorbents for chromatographic optical resolution were synthesized by grafting poly(N5-benzyl-L-glutamine-co-γ-benzyl L-glutamyl) onto cross-linked polystyrene beads. The effects of the crosslinking degree (1,5%, 9%, 30%) and the porosity of the polystyrene matrix on the resolution efficiency of the adsorbent were investigated. Similar resolution efficiencies were observed on 1,5% cross-linked gel (non-porous) and 9% cross-linked porous adsorbents, while a decline in the efficiency was observed on 30% cross-linked porous adsorbent. Studies of transmission electron micrographs of these adsorbent clearly showed the effect of degree of crosslinking on the distribution manner of the incorporated poly(α-amino acid). At a degree of 30%, clustered incorporation occurs mainly on the pore surface and not within the cross-linked polymer matrix. Such incorporation manners are also suggested by the swelling properties of the adsorbents. Pore volumes, pore radii, and specific surface areas of the adsorbents were also measured. It was observed that uniform incorporation of poly(α-amino acid) derives a higher resolution efficiency of the adsorbent.
    Additional Material: 7 Ill.
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  • 7
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer membranes having cationic charge site, poly(1-alkyl-4-vinylpyridinium iodide-co-acrylonitrile) (alkyl: methyl, butyl, or octyl) were prepared in terms of coulombic interaction for separation of water-ethanol mixtures. The incorporation of cationic charge site into the membrane led to improve not only separation factors (selectivity toward water) but also flux number in the separation of aqueous ethanol solution by pervaporation technique. Target values, which were requested to have from the viewpoint of industrial utilization for separation of aqueous ethanol solution were attained as follows: separation factor toward water over 50 and flux value over 500 g m-2 h-1, through poly(1-methyl-4-vinylpyridinium iodide-co-acrylonitrile) (membrane 3) (quarternized fraction of pyridinium moiety, 89.5%; mol fraction of pyridinium moiety, 0.034) and poly(1-butyl-4-vinylpyridinium iodide-co-acrylonitrile) (membrane 5) (quarternized fraction, 100%; mol fraction of pyridinium moiety, 0.038). It was found that the introduction of cationic charge site into the membrane was one of feasible methods to obtain suitable membranes for water permselective membranes in the separation of water-ethanol mixtures.
    Additional Material: 15 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 1585-1597 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separation of water-ethanol mixture through a membrane was carried out by pervaporation using a membrane which provided a hydrogen-bonding interaction. A membrane obtained from poly(acrylic acid-co-acrylonitrile) was effective for a selective separation of water from aqueous ethanol solution by pervaporation technique. Spectroscopic and flux analyses verified that this high selectivity toward water was attributed to the hydrogen-bonding interaction between water and acrylic acid (carboxylic acid) unit in the membrane. On the other hand, a membrane from poly(acrylic acid-co-styrene) preferentially permeated ethanol in the low water feed concentration region.
    Additional Material: 9 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 2959-2969 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small unilamellar liposomes were prepared in an aqueous medium by the sonication of phospholipids containing diene or triene groups in their hydrocarbon acyl chains. These liposomes were polymerized by gamma-ray irradiation. Conversion of polymerization was successively followed by UV spectrometry. Diene-type lipid liposomes were revealed for which a gamma-ray dose of 0.8 Mrad was required for complete polymerization and which were polymerized more easily than triene-type lipid liposomes. Triene-type lipids required 2.3 Mrad gamma ray to polymerize them completely. Contrary to UV-irradiation polymerization, there was no concentration dependence on the polymerization. Structure of the polymerized liposomes were confirmed by electron microscopy as small unilamellar liposomes. Study on the leakage of fluorescein from inner aqueous phase of the polymerized liposomes revealed that polymerized triene-type liposomes were relatively more stable than the polymerized diene-type liposomes.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 335-340 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
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