摘要:

AbstractBy reacting a rigid rod epoxy terminated molecule (p‐bis(2,3‐epoxypropoxy)‐α‐methylstilbene) with an aliphatic carboxylic acid (decanedioic acid), a lightly crosslinked liquid crystalline network is obtained. This network exhibits a smectic‐like phase. While the mesophasic structure resulted “frozen” by the crosslinks in the case of higly crosslinked liquid crystalline epoxy resins, in this case a reversible transition from the liquid crystalline to the isotropic phase is observed. Moreover, while curing the same rigid rod epoxy molecule with amines resulted in a thermoset with a nematic structure, in this case a more ordered mesophase can be obtained. Preliminary results show that it is possible to orient macroscopically the mesogenic chains by stretching thin films above the glass transition temperature (Tg) and then quickly cooling down to the glassy state. This makes this material very attractive in the field of optica

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160201

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractPhase transitions of poly(dialkylsiloxane)s substituted with propyl and butyl groups are reported based on X‐ray diffractometry. The structure in the mesophase and in the melt of polymers with 2 to 10 carbon atoms in each side chain is compared. Both phases display a linear dependence of the molecular cross‐section on the length of the alkyl group demonstrating their structural similarity. By means of differential scanning calorimetry it is shown that the temperature range of the mesophase remains practically unchanged in width as well as in absolute temperature for dibutyl up to dihexyl substituted polysiloxa

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160202

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractCopolymerization of ethylene and 1‐butene were performed using the catalyst system TiCl3· 1/3 AlCl3/MgCl2/THF with or without partial activation by AlEt2Cl. The catalyst and the copolymers were characterized by IR spectroscopy. The experimental results reveal that partial activation strongly affects the catalytic sensitivity toward 1‐butene and obviously leads to a two‐step polymerization rate p

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160203

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe propagation rate coefficient of the terpolymerization of styrene, methyl methacrylate and methyl acrylate in bulk was successfully determined at three different monomer compositions. The temperature was varied between 18 and 80°C. The resulting data at 50°C were not in agreement with predictions according to the terminal model with binary reactivity ratios that have been determined by fitting copolymer composition data with the terminal model. This indicates that here also the penultimate unit affects the kinetic

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160204

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe implementation of the step‐scan technique on our FT‐IR spectrometer enabled us to follow the electric‐field induced reorientation dynamics of different molecular segments of a ferroelectric liquid crystalline polymer on a sub‐millisecond time scale. It was detected that not only the mesogen but also the spacer and at least part of the backbone take part in the reorientation

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160205

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractSelective salt transport of KCl over LiCl has been studied for a crosslinked poly(L‐glutamic acid) membrane immersed in 80 vol.‐% ethanol. The permeabilities (Ps) and solubilities were measured for various mixing ratios of the salts. The highest permselectivity (Ps(KCl)/Ps(LiCl) = 4,3) has been obtained at a LiCl mole fraction of 0,2. It is similar to that obtained in single salt syst

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160206

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractBased on the Michael reaction of multifunctional acetoacetates with multiacrylates, in the presence or absence of dimethacrylates, tailor made matrix materials can be prepared. This can be achieved in a one‐ or two‐step process. The Michael addition (first step) can be followed by radiation curing of excessive acrylate (second st

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160207

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractNovel semi‐rigid fluorocarbon‐containing coplycarbonates composed of biphenyl moiety and rigid rod‐like hexafluoropentane chain were prepared by melt polycondensation of 6,6′‐(biphenyl‐4,4′‐diyldioxy)dihexanol (1) and 2,2,3,3,4,4‐hexafluoro‐1,5‐pentanediol (2) with alkylene diphenyl dicarbonates3of various aliphatic lengths (m= 6, 8, 10 and 12). The structures of the copolymers4were confirmed by FT‐IR,1H and13C NMR spectra and elemental analyses. The thermal and liquid‐crystalline (LC) properties were examined by differential scanning calorimetry (DSC), polarizing microscopy and temperature‐changeable X‐ray analyses. These measurements indicated that the copolymers show well‐defined thermotropic nematic textures and have block‐like sequences. It is suggested that the introduction of the hexafluoropentane chain into the main

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160208

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe synthesis of substituted poly(p‐phenylenenvinylene) (PPV) was carried out via metathesis polycondensation of 2,5‐diheptyl‐1,4‐divinylbenzene (DHepDVB). A stable molybdenumcarbene complex served as catalyst. The preparation of the educt employed (DHepDPV,3a) is described. The obtained poly(2,5‐diheptyl‐1,4‐phenylenevinylene) (DHepPPV,5), an intensely yellow product, has an all‐trans‐configuration and, with a degree of polymerization of ≈ 10 is soluble in convention

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160209

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY