摘要:

AbstractA bicyclic pseudourea, 2,3,5,6‐tetrahydroimidazo[2,1‐b][1,3]oxazole (1), was isolated for the first time, and its cationic and spontaneous polymerizations were examined. Both polymerizations gave poly(1,3‐imidazolidin‐2‐one‐1,3‐diylethylene) (2) in high yields. The polymer is a crystalline solid with glass transition and melting temperature of 51°C and 286°C, respectively. Thermogravimetry showed that it is stable up to 450°

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181001

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn characterizing the overall orientation of polymers by infrared (IR) dichroism, the orientation function must be obtained from the dichroic ratios of conformationally insensitive bands. Identification of such bands is thus necessary prior to the calculation of the orientation function. In this study, we devise two simple methods for evaluating the conformational sensitivities of IR bands from the measurement of the dichroic ratio. Both methods are based on the fact that the orientation function calculated by all conformationally insensitive bands should be identical, while this is not true for conformationally sensitive bands. Poly(ether ether ketone) (PEEK) is used as an example to demonstrate the use of these methods.

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181002

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPoly[styrene‐co‐(N‐vinylcarbazole)] copolymers with controlled molecular weights and narrow polydispersities were synthesized by nitroxide‐mediated “living” free radical copolymerization using an initiator/capping agent system consisting of benzoyl peroxide (BPO) and the stable nitroxyl radical 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO). The copolymerization behaves in a “living” fashion and allows the synthesis of poly[styrene‐co‐(N‐vinylcarbazole)]/polystyrene block copolymers via a controlled chain‐extension reaction of the pre

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181003

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractHeterogeneous ampholytic gels were prepared by two‐step γ‐irradiation of aqueous solutions of poly(vinyl alcohol)s having sulfonate and quaternary ammonium groups, respectively. A reference gel was prepared by one‐step irradiation. The heterogeneous gels turned out to swell to lesser degrees with increasing ionic strength of the immersing solution than the reference gel. However, the ion‐specific swelling and deswelling behavior, which had been found for the reference gel, was also observed for the present heterogen

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181004

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA series of 2,3‐O‐carboxymethylcelluloses (CMC's), which are regioselectively substituted at the C‐2 and C‐3 position, were prepared and their water solubility was examined. It was found that the lower limit for the degree of substitution (DS) value of water‐soluble 2,3‐O‐CMC is about 0.3. This value was almost the same as that of CMC prepared in a slurry of isopropyl alcohol/water with isopropyl chloroacetate and sodium hydroxide, showing that the uniform alkylation is rather important to convert cellulose into water‐solu

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181005

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe surface of silica particles has been chemically modified with oligo‐ or poly‐(α,1←4)‐D‐glucopyranose (amylose) chains of various length by covalently attaching maltoheptaose derivatives to the solid support and enzymatic polymerization of glucose‐1‐phosphate with potato phosphorylase (E.C. 2.4.1.1) as catalyst. The characterization of the products by solid‐state NMR spectroscopy showed an interesting dependence of the linewidth with the grafting density of the glucan chains. The modified silica particles showed chiral discrimination in liqui

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181006

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe exposure to pentane vapour of poly(3‐alkylthiophene)s with different alkyl chains produces a modification in the optical properties of the thin films. The treatment induces a red‐shift of the electronic absorption maximum and the appearance of vibronic structure in the UV spectra. We have followed these changes with IR and Raman spectroscopies to monitor the modification of the backbone conjugation, and with X‐ray diffraction to evidence the structural order of the c

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181007

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractNovel linear polymer/dendrimer block copolymers, poly(2‐methyl‐2‐oxazoline)‐block‐poly(amido amine) dendrimers (water‐soluble full‐generation type4(G= 4.0 and 5.0) and amphiphilic half‐generation type5(G= 3.5, 4.5, and 5.5)), were synthesized by divergent‐growth dendrimer construction with ω‐ethylenediamine‐terminated poly(2‐methyl‐2‐oxazoline), which was prepared by living ring‐opening polymerization of 2‐methyl‐2‐oxazoline. Assembly of the amphiphilic dendrimer‐based block copolymer (G= 5.5) was investigated by surface tension measurements (critical micelle concentration, 0.49 wt.‐%) and by small‐angle neutron scattering analysis (spher

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181008

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY