摘要:

AbstractThe transport behaviour of hydrocarbon gases through liquid‐crystalline (l.c.) elastomers is investigated. For different l.c. elastomers exhibiting the smectic‐A phase structure, diffusion and permeation coefficients and solubilities are measured as a function of temperature. The behaviour at the smectic‐A to isotropic phase transformation is discussed and the permeabilities of propane through different l.c. membranes are compared with respect to their network type, spacer length and end group of the mesogens. In methacrylate networks with high phase transformation enthalpies a discontinuous behaviour is observed at the smectic to isotropic phase transformation temperatureTc, as expected for a first‐order phase transformation. Depending on the chemical constitution of the membrane, the l.c. state can reduce or improve the gas transport compared to the isotropic state. With increasing flexibility of the membrane system — caused by a more flexible network, longer spacer or longer end group — the permeabilities exhibit significantly higher values. For all elastomers an increase of the ideal selectivities is observed in the smec

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931201

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThis paper describes the ring‐opening methathesis polymerization of homopolymers and copolymers ofexo‐ andendo‐2‐cyanobicyclo[2.2.1]hept‐5‐ene (norbornenenitrile) in solution. Polymerization kinetics were followed via1H NMR spectroscopy in real time while the final polymer microstructure was determined via13C NMR. While pureendomonomer does not polymerize readily, it copolymerizes withexomonomer, rapidly and to high conversions. The structure of the copolymer appears to be quite similar to that ofexohomopolymer. We conclude thatexomonomer adds directly to eitherexoorendo, whileendo‐endoaddition is steric

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931202

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA polymeric solid electrolyte with high ionic conductivity was prepared by complexing a polyurethane elastomer with LiClO4. The ionic conductivity of these complexes increases proportional to the increase of the content of poly(tetramethylene oxide) component in the polyurethane elastomer and with increasing LiClO4concentration, and reaches a value of 10−4S/cm at 80°C for [LiClO4] = 1,20 mmol/g polymer. The polyurethane elastomer‐LiClO4complex has good mechanical properties compared with poly(ethylene oxide)‐and poly(propylene oxide)‐based c

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931203

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA partially hydrolyzed ethylene/vinyl acetate (EVA) copolymer was modified through the covalent binding of a heparin‐complexing polymer, in order to improve its blood compatibility. Two different heparinizable polymeric materials (EVAPA I and II) were obtained by a two‐step reaction between an ethylene/vinyl alcohol/vinyl acetate (EVALVA) terpolymer and a poly‐(amido‐amine) (N2LL) using either hexamethylene diisocyanate (HMDI) or 1,1'‐carbonyldimidazole (CDI) as bifunctional agents. EVALVA terpolymer was prepared by a homogeneous saponification process, and the percentage of hydrolysis was determined by an analytical method. EVAPA I and II syntheses were followed by FT‐IR/ATR (Fourier Transform Infrared/Attenuated Total Reflection) s

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931204

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractRing‐opening alternating copolymerization of maleic anhydride and epichlorohydrin was carried out at 70°C with rare earth coordination catalysts composed of Nd[(RO)2PO2]3(R = CH3(CH2)3CH(C2H5)CH2)and trialkylaluminium. Anlaysis of end‐groups showed that the copolymer chain contains one OH and one CHCHCOCH2CH(CH3)2end‐group. IR, UV‐Vis,1H NMR and GPC results imply that a catalyst‐maleic anhyride complex is formed in the initiation step that the ring‐opening copolymerization proceeds via coordinate insertion mechanism accompa

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931205

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPolymers and copolymers based on the monomethacryloyl ester and the vinylbenzyl ether of sucrose, bearing either blocked or free hydroxyl groups, were synthesized in the presence of free‐radical catalysts, and their structures and dimensions were characterized. A range of copolymers of styrene andO‐methacryloylsucrose was prepared. Reactivity ratios of the comonomers were calculated by the extended Kelen‐Tüdős method. The influence of the hydroxyl groups of the sucrose moiety on the thermomechanical properties was assessed by comparing the glass transition temperatures of both blocked and unblocked copolymers. Their solubility characteristics were also determined, and it was shown that the hydrophilic‐hydrophobic properties can be controlled by the amount of sucrose methacrylate in the

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931206

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractSoluble or insoluble polystyrenes with hydroxyl‐containing polyetheramine structures were prepared by the reaction of linear or crosslinked polystyrenes containing haloalkyl, tosyloxyalkyl, or epoxy groups with bis(2‐(2‐hydroxyethoxy)ethyl)amine(ATEG). The soluble polystyrenes with ATEG residue afforded polymeric alkoxides by the reaction with aqueous NaOH or KOH under two‐phase conditions. The introduction of oxygen‐containing spacer chains between ATEG residue and the polymer backbone resulted in the formation of cryptand‐like alkoxides, in which the counter cations were bound by cooperative coordination of the oxygen donors in the ATEG residue and in the spacers. The soluble and insoluble polymers with ATEG residue exhibited high catalytic activity for the dehydrobromination of 2‐bromoethylbenzene with aqueous NaOH or KOH under two‐and three‐phase conditions, respectively. The extra coordination of the oxygen donors in the spacers resulted in increased c

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931207

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly[N‐(2‐hydroxyethyl)‐L‐glutamine] (PHEG) is a suitable carrier for the design of macromolecular prodrugs. A method is described for partial conversion of hydroxyl side groups into reactive carbonate esters. Activation is achieved through the reaction with 4‐nitrophenyl chloroformate. It is shown that during the course of the activation no intra‐ or intermolecular carbonate esters are formed. The content of reactive carbonates can, for a given set of reaction conditions, be controlled by the amount of chloroformate added. The activated polymer easily reacts with numerous amines. Reaction with a melphalan prodrug and amino‐terminated glycosides demonstrated the feasibility of the presently described activation method to prepare macromolec

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931208

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe phase separation behavior of graft copolymers containing poly(methyl methacrylate) grafts attached to a side‐chain liquid‐crystalline backbone is described and examined with respect to the share and the length of the grafts. Only copolymers with a low PMMA content show microphase separation. An increasing PMMA content leads to a miscibility of the compone

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931209

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractNew acrylate based polymers, with the potential to be converted to polyphenolic polymers — poly[2‐(4‐benzyloxyphenyl)ethyl acrylate] (4) and poly[3‐(4‐benzyloxy‐3‐methoxyphenyl)propyl acrylate] (9) — were prepared from the corresponding monomers 3 and 8 by free‐radical polymeri‐ zation, initiated by 2,2′‐azoisobutyronitrile (AIBN). The acrylate monomers, 2‐(4‐benzyloxy‐ pheny1)ethyl acrylate (3) and 3‐(4‐benzyloxy‐3‐methoxyphenyl)propy1 acrylate (8), were synthes‐ ized from acryloyl chloride and the corresponding alcohols — 2‐(4‐benzyloxyphenyl)ethanol(2) and 3‐(4‐benzyloxy‐3‐methoxyphenyl)‐ 1 ‐propano1 (7), respectively. The monomer 7 was prepared from 3‐(4‐benzyloxy‐3‐methoxyphenyl)‐1‐propene (6) by hydroboration/oxidation and 6 was obtained from eugenol(4‐allyl‐2‐methoxyphenol) as the starting material. The compounds were characterized by1H NMR,13C NMR, FTIR, and elemental analyses. The molecular weight of the

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931210

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY