摘要:

AbstractA main‐chain elastomer was synthesized for the first time by a cross‐linking hydrosilylation of a cyclosiloxane with a new main‐chain liquid crystalline semiflexible polyether. Imposing a uniaxial mechanical field to the unstretched nematic polydomain sample results in a macroscopic alignment of the director. For this process the sample has to be stretched by a factor of about 5, which considerably exceeds the effect observed for nematic side‐chain ela

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180501

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAB diblock copolymers consisting of PBLG as the hydrophobic part and PNIPAAm as the hydrophilic one were prepared by polymerization of BLG‐NCA with semitelechelic PNIPAAm with amino end group as initiator. The core‐shell type nanoparticles of the block copolymers were obtained by the diafiltration method. The sizes of the nanoparticles were from about 73 to 359 nm and the shapes of them were spherical. The release for indomethacin (IN) from the nanoparticles was faster at 28°C than at 34°C due to the conformational change of PNIPAAm by temper

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180502

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractIn this report we describe a very convenient synthetic method for the preparation in high yields and purity of cyclic [N3P3(OCH2CF3)6] and [N3P3(OC6H4R)6] (R = Br, CN, CHO, COC6H5, COCH3, H, OCH3), and polymeric [NP(OC6H4R)2]n(R = Br, CHO, COC6H5, H, But) phosphazenes from the direct reaction of the trimer [N3P3Cl6] or the high polymer [NPCl2]nand the alcohol HOCH2CF3or thepara‐substituted phenols HOC6H4R, using Cs2CO3as proton abstractor and acetone or tetrahydrofuran as so

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180503

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractElectron spin resonance (ESR) is a sensitive tool to detect the electron‐transfer processes in some specified systems from the change of the ESR signals. In this paper, the interaction between poly(N,N‐dimethylaniline) (PDMA) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) was investigated by ESR spectra based on the stability of their radicals in ethanol. It is shown that an electron‐transfer process occurs from nitrogen atoms of PDMA molecules to those of DPPH molecules which makes PDMA form more stable radical cations and eliminates the radic

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180504

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA novel synthesis of linear acrylic acid containing polymers, poly(styrene‐co‐acrylic acid) and poly(acrylic acid), was accomplished through hydrolysis of the respective parent polymers, i.e. poly(styrene‐co‐methyl acrylate) and poly(methyl acrylate), with trimethylsilyl iodide under mild conditions. Combination of1H NMR,13C NMR, FTIR, DSC and chemical titration confirms that the conversion from methoxycarbonyl to carboxyl is almost complete. This method is further successfully applied to synthesize poly‐(ethyl methacrylate‐co‐acrylic acid) through selective hydrolysis of the methyl acrylate units in poly(ethyl methacrylate‐co

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180505

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractStar polymers of tetrahydrofuran (polyTHF) were prepared by reaction of living polyTHF with diethylene triamine (DETA) in the presence of 2,2,6,6‐tetramethylpiperidine (TMP) as proton trap. The influence of several reaction parameters on the end‐capping reaction was studied in order to produce stars having varying number of arms. With a starting living polyTHF with a molecular weight of 1600, star‐shaped polymers containing up to seven polymer chains could be prepared. When the molecular weight of the living polyTHF was 8000, at most five polymer chains could be grafted on the DETA. Some physical properties of the star polymers were compared with those of their linear counterparts of the same molecular w

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180506

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA series of new macrocyclic aromatic esters have been efficiently synthesized fromo‐phthaloyl dichloride and various bisphenols, and unambiguously characterized by a combination of GPC, MS(FAB), FTIR and NMR. These macrocyclic oligomers undergo facile ring‐opening polymerization in the presence of anionic initiators to give high molecular weight polyaryla

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180507

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractTwo etching techniques are used to reveal the morphology of PC/PBA‐cs‐PMMA blend. One is based on acetic acid (CH3COOH) solutions, whereas the other uses CCl4/C2H5OH (3/1 v/v). The latter approach shows to be more appropriate and successful for revealing the morphology of PC/PBA‐cs‐PMM

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180508

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA two‐step conventional laboratory process was developed for the synthesis of mono‐ and difunctional linear and three‐arm startert‐chlorine‐telechelic polyisobutylenes (PIB) with desired molecular weights (MW) and narrow molecular weight distribution (MWD) by living carbocationic polymerization (LCCP). This polymerization method applies easy to handle operations and chemicals. LCCP of isobutylene (IB), was carried out in CH2Cl2as solvent and with BCl3as coinitiator in the first step to obtain soluble low MW PIB prepolymer with narrow MWD. This was followed by addition of hexane, TiCl4and additional monomer in the second step to prepare PIBs with desired MW and narrow MWD in practically any suitable MW region. Comparison of the one‐step and two‐step processes is a

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180509

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractNew supported catalysts on the basis of cyclopentadienylindenylzirconium dichloride (CpIndZrCl2) anchored on silica with a trisiloxane spacer (ZATS) and a pentamethylene spacer (ZAPM) were prepared and used for ethylene polymerization with modified methylaluminoxane (MAO) as cocatalyst. ZATS and ZAPM produce polyethylene with lower molecular weight but show higher activity than silica‐supported CpIndZrCl2which was prepared by reacting zirconocene directly with silica, i.e., the activity of silica‐supported CpIndZrCl2is enhanced by introducing a spacer between silica surface and metallocene spec

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180510

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY