摘要:

AbstractMorpholine‐2,5‐dione derivatives having substituents with benzyl‐protected carboxylic acid, benzyloxycarbonyl‐protected amine andp‐methoxy‐protected thiol groups, respectively, were prepared in 29–58% yield by cyclization of the correspondingN‐[(2RS)‐bromopropionyl]‐L‐amino acids. Polyesteramides with protected pendant functional groups were obtained by ring‐opening copolymerization of either ϵ‐caprolactone orDL‐lactide with morpholine‐2,5‐dione derivatives having protected functional substituents. The copolymerizations were carried out in the bulk at 130°C using stannous octoate as an initiator and using low mole fractions (0,05, 0,10 and 0,20) of morpholine‐2,5‐dione derivatives in the feed. The molecular weight of the resulting copolymers ranged from 1,4 to 8,3 · 104. The ring‐opening homopolymerization of morpho‐line‐2,5‐dione derivatives with protected functional substituents was not successful. Polyesteramides with either pendant carboxylic acid groups or pendant amine groups were prepared by catalytic hydrogenation of the corresponding protected copolymers. Treatment of copolymers having pendantp‐methoxybenzyl‐protected thiol groups with trifluoromethanesulfonic acid resulted not only in the removal of thep‐methoxybenzyl group but also in severe degradation of the cop

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931101

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly(dimethylphosphazene) crystals have been grown by two techniques, namely: (a) dilute‐solution crystallization and (b) from the supercooled melt. An orthorhombic crystal form witha= 1,390 nm,b= 0,598 nm andc= 0,473 nm was deduced from electron and X‐ray diffraction. There are four monomers per unit cell of density 1,267 g/cm3. Streaks connecting the (hk0) reflections in electron diffraction are suggestive of lattice defects along the[b]axis. Whenever crystals are annealed just belowTmwhere sufficient mobility exists, the “streaks” are absent when the specimen is cooled to room temperature. Differential scanning calorimetry (heating) exhibits two endothermic peaks at 142°C and 146°C, corresponding toT(1) andTmtransitions, respectively. A mesophase exists between these closely spaced peaks. A wider mesophase range is encountered in poly(oxyphos

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931102

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractAn ethylene/vinyl alcohol copolymer (EVA)‐copper complex membrane was prepared by casting an EVA‐CuCl2mixture (solvent: water‐propanol (1:1 v/v) mixture) on a polyethylene substrate and then immersing it in 0,1 M KOH aqueous solution. In the membrane, Cu was distributed asymmetrically in the direction of the membrane cross section. The distribution of Cu could be controlled by the temperature during preparation. The oxidation of hydroquinone during permeation through the complex membrane was performed using membranes with different Cu distribution. This distribution influences the permeation reaction. These results are well reproduced by a relation composed of Fick's law and Michaelis‐Menten type reaction kinetics. Therefore, a good reactor can be developed by controlling the catalyst distr

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931103

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPropene was polymerized with conventional and Solvay‐type TiCl3combined with Al(C2H5)2Cl using Zn(C2H5)2as a chain transfer reagent. The produced terminal Zn‐carbon bonds of the polymer were reacted with carbon dioxide and chlorine in the presence ofN‐methylimidazole followed by hydrolysis to obtain terminally carboxylated and chlorinated poly(propylene) in approximately 50%

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931104

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe kinetics of the addition reaction of methacrylic acid (1) and 2,2‐bis[4‐(2,3‐epoxypropoxy)‐phenyl]propane catalyzed by tertiary aliphatic amines, aromaticN‐heterocycles and quaternary ammonium salts, respectively, was studied in bulk with equimolar amounts of functional groups from room temperature to 120°C. A reaction order of 1,5 with regard to the conversion of epoxy as well as carboxylic groups was observed. This can be explained assuming the formation of an ammonium alkoxide ion pair by the equilibrium reaction of an epoxy group with ammonium carboxylate and the irreversible consecutive reaction of the ion pair with (1) under formation of 2‐hydroxyester groups and regeneration of ammonium carboxylate. The reaction rate constants increase linearly with the concentration of the catalyst and increase with increasing basicity of alkylpyridines. The advantage of the aromaticN‐heterocyclic catalysts consists in their stability to peroxides which are ingredients of preparations together with the epoxy methacrylate Bis‐GMA, e. g. in dental composit

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931105

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe intramolecular mobility of copolymers4was investigated by means of dielectrospectroscopy. The copolymers exhibit a convenient model for the study of local mobility in side‐chain thermotropic polymers without spacer. The dependencies of the dielectric losses on frequency and temperature point to the presence of relaxation processes related to the intramolecular mobility of fragments of the mesogenic group. For the formation of the liquid‐crystalline state two factors are important: different forms of local mobility inside the mesogenic groups and a flexible connection between side chain and main ch

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931106

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractEmulsion polymerizations of styrene with various phospholipids as emulsifiers were carried out to obtain latices bearing the lipids. Using 1‐palmitoyl‐2‐(4‐vinylbenzoyl)‐sn‐glycero‐3‐phospho‐choline(2a)and 1‐[5‐(4‐vinylphenyl)pentanoyl]‐sn‐glycero‐3‐phosphocholine(3)as emulsifiers, latices of narrow size distributions were produced in high yields with a water‐soluble initiator, K2S2O8. The lipids were found to be quantitatively immobilized onto the latex surface. With a hydrophobic initiator, 1‐palmitoyl‐2‐[5‐(4‐vinylphenyl)pentanoyl]‐sn‐glycero‐3‐phosphocholine(2c)were bound densely on the latex surface, although the yields were not high. Phospholipase C w

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931107

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIt has been recently shown thata‐halogeno ether, when activated by a weak Lewis acid such as ZnX2, may be used as initiator for the living cationic polymerization of vinyl ethers. A route to thea‐halogeno ether function is the action of dry hydrogen halide on an alcohol in the presence of an aldehyde or a cyclic acetal. The quantitative preparation of α‐chloro ethers by this route, as well as the use of such compounds to initiate the “living” cationic polymerization of vinyl ethers, was examined. This procedure was then applied to hydroxy‐telechelic polybutadiene to give a macro‐initiator with α‐chloro ether terminal groups. The latter was used to initiate the polymerization of vinyl ethers. The synthesis of poly(butadiene‐block‐ethyl vinyl ether) and poly(butadiene‐block‐2‐chloroethyl vinyl ether) is reported, as well as the preparation of other copolymers by chemical modification of the ch

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931108

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractWell defined amphiphilic diblock copolymers, consisting of an oligomeric quaternary ammonium block, a so‐called ionene, and a polystyrene block, were synthesized. The route started with the preparation of monofunctionalized polystyrene by anionic polymerization, using 3‐(dimethyl‐amino)propyllithium as initiator. The polystyrene was obtained with relatively narrow molecular weight distributions (M̄w/M̄n= 1,2–1,4). This polystyrene was coupled stepwise with a number of different monodisperse oligomer units of 2,4‐ionene, having reactive end‐groups, resulting in a monodisperse 2,4‐ionene block. End‐group titration, size exclusion chromatography, thin‐layer chromatography and infrared spectroscopy were utilized to characterize the polymers. Additionally the block copolymer in combination with tetrasodium phthalocyaninatocobalt(II)tetrasulfonate (CoPc(NaSO3)4) was tested as co‐catalyst in the phase‐transfer‐catalyzed autoxidation of 1‐dodecanethiol. Very high catalytic activities (775 mol O2/(mol Co · s)) were achieved, 40 times higher as compared with the polymer‐free system, due to a combination of the formation of the most active species and hydrophobic interaction with the hydrophobic thiol. This hydrophobic interaction resulted in an enhancement of the autoxidation rate by a factor 2,5, compared with the analogous hydr

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931109

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractA modified route to prepare oligodimethylsiloxane (ODMS) containing a quaternary salt at the one chain end was investigated, for the development of a silicone‐based transdermal penetration enhancer.p‐(Chloromethyl)phenethyl‐terminated ODMS (CMP‐ODMS) was prepared by hydrosilylation ofp‐chloromethylstyrene with hydrosilyl‐terminated ODMS, as an intermediate. Then, CMP‐ODMS was reacted with pyridine or ethyldimethylamine to afford a quaternary ODMS salt quantitatively. The enhancing activity of drug penetration was evaluated by measuring the amount of indomethacin permeating through the skin, using a two‐chamber diffusion cell having an isolated rabbit abdominal skin mounted between half cells. The obtained polymers effectively enhanced the drug penetration through the skin, whereupon the permeation coefficients were 2 to 15 times that measured without enhancer. Also, the enhancing activities were influenced by the chemical structure of polar and non

ISSN:0025-116X    

DOI:10.1002/macp.1992.021931110

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY