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  • Polymer and Materials Science  (45)
  • 1995-1999  (45)
  • 1955-1959
  • 1998  (45)
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of a diphenylethylene derivative carrying aromatic tertiary amine groups and its use in chain end functionalization of alkyllithium-initiated polymerizations (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2185-2191 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1,1-Bis[(4-dimethylamino)phenyl]ethylene was successfully synthesized through the ‘Wittigtype’ reaction of 4,4′-bis(dimethylamino)benzophenone with the ‘Tebbe’ reagent. The methylenation yields were over 80 wt.-% on the basis of the initial amount of benzophenone derivative used. Terminally functionalized polymers having aromatic tertiary amine groups at one end or at both ends were prepared by the crossover reactions of n-butyllithium (n-BuLi), poly(styryl)lithium (PSLi), and poly(isoprenyl)lithium (PILi) with the diphenylethylene analogue. The functionalization yields were over 87 mol.-% based on the results of 1H NMR spectroscopic analysis. The number-average molecular weights of the polymers based on the ratio [gram of monomer]/[mole of initiator] are in good accordance with those observed from size exclusion chromatographic and 1H NMR spectroscopic analysis (3,0 × 103 ∼ 7,5 × 103 g/mol).
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Comparison of activities of homogeneous Ti-based catalysts in the presence of methylaluminoxane (MAO) for synthesis of syndiotactic polystyrene by UV/visible spectroscopic study (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1733-1741 
    Details
    ISSN: 0887-624X
    Keywords: homogeneous Ti-based catalyst ; methylaluminoxane ; catalytic activity ; UV/visible spectroscopy ; syndiotactic polystyrene ; polymorphic structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic activities in syndiospecific polymerization of styrene in hydrocarbon using homogeneous Ti-based catalysts in the presence of methylaluminoxane (MAO) were investigated through UV/visible spectroscopic analysis. A strong UV absorption band of CpTiCl3, itself, incipiently appeared at λmax = 400 nm in toluene, followed by a bathochromic shift with its remarkable decrease by the addition of MAO. The absorption band intensity at λmax = 400 nm arising from delocalization of π-electrons on the cyclopentadienyl ring decreased by methylation in the presence of MAO with regard to the mechanism for production of an active center (“cation-like”), for example, the change of the ionic nature. The intensity decrease at λmax = 400 nm was suppressed over 2000 of the [Al]/[Ti] ratio. In the case of Ti(OC4H9)4 having a σ-ligand, new and broad UV absorption bands were developed at λmax = 340 nm and 410 nm in the presence of MAO in contrast with the CpTiCl3/MAO system. Comparison between the relative absorption intensities at λmax = 340 nm and 410 nm led to the determination of a maximum catalytic activity of Ti(OC4H9)4 in the presence of MAO related to the polymerization yield. The maximum polymerization yield was observed with regard to the relative maximum value of the absorption intensity at λmax = 410 nm with the [Al]/[Ti] ratio (500). From observation for polymorphism of the final products via differential scanning calorimetric analysis (DSC), the thermally unstable β-form seemed to be produced by the CpTiCl3/MAO system independent of the MAO concentration, the Ti(OC4H9)4/MAO system produced a thermally stable α-form in the low MAO concentration (up to 100 of the [Al]/[Ti] ratio), and a mixture of α- and/or β-forms over 200 of the [Al]/[Ti] ratio under our experimental conditions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1733-1741, 1998
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  • 3
    Electronic Resource
    Electronic Resource
    Microstructure effect in the coupling reactions of polymeric organolithium compounds using chlorosilanes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1743-1753 
    Details
    ISSN: 0887-624X
    Keywords: coupling reaction ; living polymer ; microstructure ; coupling yield ; 1,4-enchainment ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The most important variable affecting the yield in the coupling reactions of polymeric organolithium compounds with chlorosilane compounds has been investigated through size-exclusion chromatographic (SEC) analysis. The coupling reaction of poly(styryl)lithium with dichlorodimethylsilane as a silane-coupling agent provided 44 wt % of the coupling yield. The coupling yield, depending on the chain end reactivity of active polymers, was not greatly affected. The addition of a Lewis base such as N,N,N′,N′-tetramethylethylenediamine (TMEDA) even after complete polymerization of the dienes in hydrocarbon seems to affect the coupling reaction, resulting in decreasing the yield. The 1,2- or 3,4-enchain contents in the polydiene backbones affected the reduction of the linking efficiency in the coupling of the poly(dienyl)lithiums with chlorosilanes as the linking agent. The linking yields of the active polymers including over 75 mol % of 1,2- or 3,4-enchainment on the polydiene segment were below 20 wt %. The linking yields exhibited a dependence not only on the steric requirement of the chain end, but also the microstructure of the polydiene segment. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1743-1753, 1998
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  • 4
    Electronic Resource
    Electronic Resource
    Behavior of CHO cells on phosphated cellulose membranes (1998)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 40 (1998), S. 401-406 
    Details
    ISSN: 0021-9304
    Keywords: cell culture ; CHO cells ; cellulose membrane ; phosphorylation ; cell aggregation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Phosphate groups (negatively charged chemical groups) were grafted onto the surface of cellulose membranes by a reaction between hydroxyl groups of cellulose and phosphorus pentoxide to observe the effect of phosphate groups on cellular behavior. X-ray photoelectron spectroscopy (XPS) was used to determine phosphorylation. Captive bubble contact angle measurement was used to determine surface wettability. XPS was also used to analyze serum protein adsorption. Chinese hamster ovary (CHO) cells were maintained in Ham's F-12 nutrient mixture with and without fetal calf serum. Total cell area and shape factor were analyzed using image-analyzing software. Serum proteins showed higher adsorption on phosphated cellulose. Cell spreading on phosphated membranes was greater than on the cellulose membrane that served as control. The cell growth rate was faster compared to the control. Large cell aggregates were not found on the phosphated membranes, in contrast to the control membrane. The cells on the control were aggregated regardless of the existence of divalent cations in the medium. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 401-406, 1998.
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of the polyamide molecular structure on the performance of reverse osmosis membranes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1821-1830 
    Details
    ISSN: 0887-6266
    Keywords: reverse osmosis ; poly(aminostyrene) ; benzenediamines ; acyl chlorides ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin-film composite reverse osmosis membranes of polyamides were prepared by interfacial polymerization. Various benzenediamines and poly(aminostyrene) were interfacially reacted with various acyl chlorides to prepare a skin layer of composite membranes. Among the membranes prepared from the structural isomeric monomers of benzenediamines and acyl chlorides, i.e., the same chemical composition but different in the position of functional groups on the aromatic ring, the membrane with the best salt rejection was obtained when the reacting groups forming amide are located at the same position on the aromatic ring. Membranes prepared by interfacially reacting various diamines with trimesoyl chloride revealed that the salt rejection depends on the linear chain structure of polyamides and network formed by crosslinking. Membranes obtained by interfacial polymerization of poly(aminostyrene) with trimesoyl chloride showed higher water flux but lower salt rejection than those obtained by interfacial polymerization of various benzenediamines with trimesoyl chloride. Membranes obtained here showed the typical trade-off behavior between salt rejection and water flux. However, membranes prepared by interfacially reacting trimesoyl chloride with a mixture of poly(aminostyrene) and m-phenylenediamine or a mixture of poly(aminostyrene), m-phenylenediamine, and diaminobenzoic acid showed a performance advantage over usual membranes, i.e., a large positive deviation from the usual trade-off trend. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1821-1830, 1998
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  • 6
    Electronic Resource
    Electronic Resource
    Drag reduction characteristics of polysaccharide xanthan gum (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 19 (1998), S. 419-422 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The turbulent drag reduction characteristics of the rod-like polysaccharide xanthan gum dissolved in water was investigated using a rotating disk apparatus. The ultrasonic degradation method was adopted to obtain polymer fractions of different molecular weights of xanthan gum for this study. The drag reduction curve was then plotted to observed the universal characteristics of xanthan gum, and the intrinsic concentration was found to be an extremely useful quantity in normalizing the drag reduction data for different molecular weights.
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation of anthracene-labelled poly(methyl methacrylate) via atom transfer radical polymerization (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 19 (1998), S. 191-196 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Anthracene-labelled poly(methyl methacrylate) (PMMA) was prepared via atom transfer radical polymerization (ATRP) where 9,10-bis(chloromethyl)anthracene and CuCl/2,2′-bipyridine were used as the initiator and catalyst, respectively. Both the linear increase of the number average molecular mass with conversion and the narrow polydispersity in the resulting polymers suggest that the polymerization proceeds in a “living” fashion and the anthracene molecule is incorporated into the middle of the polymer backbone. The initiation efficiency was low, ca. 13%, presumably due to some side reactions which compete with the initiation reaction.
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  • 8
    Electronic Resource
    Electronic Resource
    Copolymer composition-dependent light transmission of polymer/liquid crystals composite films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 55-64 
    Details
    ISSN: 0887-6266
    Keywords: PDLC ; polarization ; angular discrimination ; copolymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electrooptic responses (voltage and angular-dependent transmittance) of polymer/liquid crystal composite films with H, V, and unpolarized lights have been studied based on a nematic liquid crystal (Ro-5921) and four types of homopolymers and copolymers from ethyl methacrylate and styrene with different compositions. In this way, the index ratio of the polymer (np) to the ordinary refractive index of liquid crystal (no)(np/no) has been varied systematically, and the effect of the index ratio on viewing angle, applied voltage, response times, and transient response have been investigated. With increasing styrene content in the copolymer, droplet size increased, threshold (Vth) and saturation (Vsat) voltage, and rise time decreased. With np ≲ no, maximum transmittance occurred at normal incidence, regardless of the type of polarization. On the contrary with np 〉 no, V-polarization gave a peak in the transmittance-voltage curve, and transmittance overshot upon removal of the field, and these were interpreted in terms of effective refractive index and two-step relaxations. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 55-64, 1998
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  • 9
    Electronic Resource
    Electronic Resource
    Photoinduced surface relief gratings in high-Tg main-chain azoaromatic polymer films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 283-289 
    Details
    ISSN: 0887-624X
    Keywords: polyurea ; azoaromatic group ; surface relief grating ; holographic material ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized two classes of polyureas with mono- and bisazoaromatic groups in their main chains via reactions between isophorone diisocyanate and the corresponding diamines. Holographic gratings were fabricated on azoaromatic polyurea films prepared by spin-coating from solutions. The effect of high glass transition temperature and dipole moment of azo groups on the formation of gratings was investigated. Although the two polymers have relatively high glass transition temperatures (197 and 236°C), chromophore alignment was induced by laser beam irradiation at modest light intensities. Regularly spaced surface relief gratings on the polymer film were also recorded upon exposure to an interference pattern of two polarized argon laser beams. Erasure could be achieved by heating above Tg or by exposure to one of the beams in a manner similar to low-Tg side-chain azo polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 283-289, 1998
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis and properties of nonlinear optical side chain soluble polyimides for photonics applications (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 301-307 
    Details
    ISSN: 0887-624X
    Keywords: polyimides ; electrooptics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aromatic polyimides with side chain nonlinear optical chromophores have been investigated through a facile two-step synthetic route. First, various poly(hydroxy imide)s have been synthesized by direct thermal imidization of diaminophenol dihydrochloride salt and aromatic dianhydride monomers. The resulting polyimides bearing phenolic hydroxy groups were found to react easily with the terminal hydroxy group on the chromophores via the Mitsunobu condensation to give corresponding polyimides with high optical nonlinearities and good solubility in common organic solvents. Detailed physical properties showed that these polyimides have a molecular weight (Mw) of 31,000 and high glass transition temperature above 220°C, ensuring a long-term alignment stability at elevated temperature. The electrooptic coefficients, r33, of the electrically poled polymer films were in the range 1.8-7.6 pm/V at 1.3 μm. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 301-307, 1998
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