摘要:

AbstractMicrogels which are soluble crosslinked polymer networks have been prepared using the nitroxide living free radical polymerization methodology. When heated in the presence oftert‐butylstyrene and 1,4‐divinylbenzene, the alkoxyamine1derived from 2,2′‐azoisobutyronitrile (AIBN) afforded a high molecular weight soluble polymer which was shown by size exclusion chromatography in conjunction with an on‐line multi angle laser light scattering (MALLS) detector to have microgel p

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180901

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAlternative molecularly imprinted polymeric membranes were prepared from a polystyrene resin bearing tetrapeptides consisting ofD‐amino acids or L‐amino acids. The membrane prepared from a DLDE derivative (H‐Asp(OcHex)‐Leu‐Asp(OcHex)‐Glu(OBzl)CH2) consisting ofD‐amino acids and imprinted by Boc‐D‐Trp recognizes the D‐isomer in preference to the correspondingL‐isomer and vice versa. The amino acid preferentially adsorbed by the membrane was selectively permeated by

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180902

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA new type of solid superacid (SO42−/TiO2/Nd3+) was used for the ring‐opening polymerization of chloromethylthiirane (CMT). TiO2· H2O immersed in a sulfuric acid solution containing Nd3+ions and calcined at 600°C gave the solid superacid for initiating the polymerization of CMT. The effects of polymerization temperature and amount of the initiator on the CMT polymerization were studied. Poly(CMT) obtained has higher molecular weight (M̄w= 52 000) than ever re

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180903

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractMultifunctional 2‐vinylcyclopropanes were synthesized by esterification of the 1‐methoxycarbonyl‐2‐vinylcyclopropane‐1‐carboxylic acid with ethylene glycol, 1,1,1‐trimethylolpropane or 1,4‐cyclohexanediol in the presence of 1,3‐dicyclohexylcarbodiimide (DCC). The structure of the new vinylcyclopropanes was confirmed by elemental analysis, IR,1H NMR and13C NMR spectroscopy. The radical polymerization of the 2‐vinylcyclopropanes in bulk with 2,2′‐azoisobutyronitrile (AIBN) results in transparent crosslinked polymers. The polymerization of the liquid monomers is accompanied by a

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180904

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractAn extendedHermans‐Endeequation for real solutions has been derived in order to calculate the density as a function of the radial distance in a density gradient mixture (light/heavy medium) inside an ultracentrifugal cell. The equation has been tested with equilibrium density gradient measurements of the system water/metrizamide/polystyrene latex where metrizamide is the heavy medium. The solvent compositions were 8 to 15 mass‐% metrizamide (2‐(3‐acetamido‐5‐N‐methylacetamido‐2,4,6‐triiodobenzamido)‐2‐deoxy‐D‐glucose). The latex concentration was 0.03 mass‐%. It is demonstrated that the density gradient is highly influenced due to monideality effects with respect to the solvent composition and due to the pressure grad

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180905

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractCarboxy‐terminated polystyrene, poly(styrene‐co‐acrylonitrile), and polystyrene‐block‐poly(styrene‐co‐acrylonitrile) with ratios of weight‐ to number‐average molar massesM̄w/M̄nbelow 1.3 were synthesized via a controlled radical polymerization mechanism. The polymerizations were initiated with 4,4′‐azobis(4‐cyanopentane‐carboxylic acid) and 2,2,6,6‐tetramethyl‐1‐piperidyloxyl radical and conducted in bulk at elevated temperatures. The polymerization was monitored by nuclear magnetic resonance, size‐exclusion chromatography, end‐group titration

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180906

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe complex [η3‐methallyl‐nickel‐dad]PF6is a new catalyst precursor for ethylene polymerization. The system is active in the presence of usual organoaluminium compounds like diethylaluminium chloride, at low Al/Ni ratios and under mild reaction conditions (temperatures between −10°C and 25°C, ethylene partial pressure from 1 to 15 atm). The polymers show extensive methyl branching, whose content is controlled by reaction parameters like temperature and ethylen

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180907

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe soluble catalyst system methylaluminoxane (MAO)‐Ni(acac), (acac: acetylacetonate) gives polystyrene consisting of an amorphous (aPS) and a crystalline isotactic (ips) fraction. Al(CH3)3, which is always present in commercial samples of MAO, decreases both polymer yield and stereospecificity. The polymer yield increases with increasing the MAO/Ni ratio but, at the same time, the iPS/aPS ratio decreases. Addition of N(C2H5)3(mole ratio N/Ni = 1) increases the proportion of the isotactic fraction, while it decreases the polymer yield. A tentative interpretation of the stereospecificity is reporte

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180908

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe chiral heterobimetallic complexes Li[Ln(η5: η1‐C5R41SiMe2NCH2CH2R2)2] (Ln = Y, Lu; C5R41= C5Me4, C5H4, 3‐C5H3tBu; R2= OMe, NMe2; Me: methyl;tBu:tert‐butyl) have been found to polymerize ϵ‐caprolactone to give a polymer of high molecular weight (M̄n<20 000) and moderate polydispersity (M̄w/M̄n<2.0). Failure to observe a correlation between monomer/initiator ratio and molecular weight suggests a polymerization mechanism different from a pseudo‐an

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180909

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA new macrocyclic arylene ether sulfone bearing two carboxylic groups,4, was prepared by use of pseudo high dilution techniques. In a first step, 4,4‐bis[4‐(4‐(4‐chlorophenylsulfonyl)phenoxy)phenyl]pentanoic acid (3) was prepared from bis(4‐chlorophenyl)sulfone (1) and an excess of 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2). Then, the purified trimer3was cyclocondensed with 4,4‐bis(4‐hydroxyphenyl)pentanoic acid (2), yielding the bifunctionalized macrocycle4. The existence of the ring‐shaped molecule was proved by use of MALDI‐TOF, NMR‐ and IR‐spectroscopy. The free carboxylic groups of4were used to build up polyamides that contain the macrocycle in the main chain and 4,4′‐diaminodiphenylmetha

ISSN:1022-1336    

DOI:10.1002/marc.1997.030180910

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY