摘要:

AbstractFree radical polymerization of methyl methacrylate (MMA) within the uniform channels of the mesoporous zeolite MCM‐41 proceeds at 100°C to give a high molecular weight polymer (PMMA). The formation of long‐living propagating polymer‐radicals is observed by electron paramagnetic resonance (EPR). The molecular weight of PMMA within the mesopores can be controlled over a wide range by changing the monomer‐to‐initiator

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181201

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe correct (event weighted) average ofkt, 〈kt〉, has been calculated for pseudostationary laser‐induced polymerization for a kinetic scheme with chain‐length dependent termination and compared to the averagek̄tobtained by formally solving forktthe expression for the second moment of the chain‐length distribution valid for chain‐length independent termination (represented by the product of rate of polymerization νpand weight average degree of polymerizationP̄w). It is shown that there is a fair agreement between the two quantities. This may be used to recover experimentally the power‐law governing the dependence ofkton chain‐length, espec

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181202

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA series of novel quinoxaline‐based conjugated polymers which contain a ruthenium(II) bipyridine complex were synthesized by the Suzuki coupling reactions. UV/VIS spectroscopy showed that the spectral features of the polymers are dependent on the amount of metal complex present. Results from excitation and emission spectroscopy suggest an energy transfer between the backbone and the metal complex. The polymers exhibit hole carrier mobilities of ≈ 10−5cm2· V−1· s−1, which is comparable to organic phot

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181203

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractSeveral nickel α‐diimine compounds of the general formula (ArNC(R)C(R)NAr)NiX2(Ar = 2,6‐alkyl substituted Ph, R = H or CH3, X = Br or CH3) were tested in ethylene polymerization after activation with different co‐catalysts, such as methylaluminoxane, Al(C2H5)2Cl or other aluminium alkyls, and ionizing reagents like B(C6F5)3, [CPh3][B(C6F5)4] or HBF4. The performances of the different catalytic systems were compared with reference to polymer productivity and structure. The degree of branching of the obtained polyethylenes was shown to depend not only on the ligand environment at the Ni centre but also on the type of

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181204

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe star‐shaped polymer withtrans‐tetrapyridyl complex of Ru(II) as a core was prepared by complexation of ester‐linked pyridyl‐terminated poly(oxyethylene) (M̄n= 2000) with a Ru5Cl122−cluster. The unimodal peak of the star‐shaped polymer in the gel‐permeation chromatogram was shifted to a higher molecular weight region than that of the starting prepolymer. The electron‐withdrawing ester substituent inparaposition of the pyridine ring shifted the metal‐to‐ligand charge transfer (MLCT) band int

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181205

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractFormic acid was found to dissolve sodium carboxymethylcellulose (Na‐CMC) with comparatively slight chain degradation. The dissolution of Na‐CMC in a wide range of degree of substitution from 0.4 to 2.0 occurs under partial formylation of the remaining OH groups of the polymer, i.e., formic acid is the first non‐aqueous, so‐called derivatizing solvent. The Na‐CMC formyl esters, which can be isolated under water‐free conditions, are even soluble in dipolar‐aprotic solvents, and they can be regenerated to Na‐CMC by treating with aqueous so

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181206

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractEnd‐functionalized (1→6)‐2,5‐anhydro‐3,4‐di‐O‐methyl‐D‐glucitols (3a–c) were synthesized by the anionic cyclopolymerization of 1,2:5,6‐dianhydro‐3,4‐di‐O‐methyl‐D‐mannitol (1), followed by treatment with a terminating agent such as 4‐vinylbenzyl (2a), oxetanyl (2b), and methacryloyl group (2c). The end‐functionalization proceeded in a high efficiency at 73–98%. The radical copolymerization of styrene with3ayielded a polymer (5a) whose GPC trace exhibited a unimodal peak.5awas polystyrene with (1→6)‐2,5‐anhydro‐3,4‐di‐O‐methyl‐D‐glucitol as pendant

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181207

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPolystyrene/poly[styrene‐co‐(butyl methacrylate)] block copolymers with controlled molecular weights and with polydispersities generally belowM̄w/M̄n= 1,45 and partially as low asM̄w/M̄n= 1,19 were synthesized by a free radical bulk copolymerization using a 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO)‐capped polystyrene macroinitiator. The influence of the macroinitiator concentration on the block copolymerization was studied. The polymerization rates are independent of the macroinitiator concentration and are close to that of thermally self‐initiated styrene/butyl methacrylate copolymerizations showing the important role of self‐initiation forN‐oxyl mediated free ra

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181208

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractMono and difunctional polystyrenes containing active halogenated end groups were prepared by atom transfer radical polymerization (ATRP). Substitution reactions were explored to convert the halogen termini to azido groups, followed by readuction to form the amino functional polymer. Quantitative conversion of the end groups was observed in each transformation reaction.1H NMR demonstrated the formation of the azide from the bromide functionality without elimination. The difunctional α,ω‐diaminopolystyrene was reacted with terephthaloyl chloride in a condensation process to produce chain‐extended polystyrene containing amide bonds along the polymer bac

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181209

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPoly(2‐alkyl‐2‐oxazoline)s having an acrylate group at both chain ends were synthesized by terminating living bifunctional poly(2‐methyl‐2‐oxazoline) or poly(2‐ethyl‐2‐oxazoline) with acrylic acid. These macromonomers have been polymerized to the corresponding polyoxazoline networks. Thermal as well as UV‐initiated free radical polymerization were applied and the influence of the polymerization conditions and molecular weight of the prepolymer used on the properties of the networks were investigated. Both methods of polymerization produced high fractions of soluble material, probably due to the low concentration of the

ISSN:1022-1336    

DOI:10.1002/marc.1997.030181210

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY