摘要:

AbstractThis paper describes the polymerization of 2‐methyl‐(3,6‐di‐O‐benzyl‐ 1,2‐dideoxy‐α‐D‐glucopyrano)‐[2,1‐d]‐2‐oxazoline (1) with an acid catalyst. The polymerization proceeds involving stereoregular glycosylation to give polysaccharide2. The polymer structure, 2‐acetamido‐3,6‐di‐O‐benzyl‐2‐deoxy‐(l→4)‐β‐D‐glucopyranan was determined by means of1H NMR,13C NMR, and IR spectra as well as elemental analysis. The molecular we

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170601

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe cationic ring‐opening polymerization of trimethylene urethane (tetrahydro‐2H‐1,3‐oxazin‐2‐one) in the melt with methyl trifluoromethanesulfonate as initiator results in poly(trimethylene urethane) in yields of ≈70%. Under the same reaction conditions 2,2‐dimethyltrimethylene urethane (5,5‐dimethyltetrahydro‐2H‐1,3‐oxazin‐2‐one) cannot be polymerized. Poly(2,2‐dimethyltrimethylene urethane), however, was obtained via polycondensation polymerization. Both polymers exhibit a uniform microstructure as deduced from NMR spectroscopic analysis. Ring‐closing depolymerization in the melt with dibutyltin dimethoxide or titanium tetraisopropoxide at 140°C results the respe

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170602

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractDialkyl iodomethylmalonates in the presence of tetrabutylammonium iodide initiate the polymerization of methyl methacrylate, but not of methyl acrylate or acrylonitrile. Typically, at 60°C in 1,3‐dimethyltetrahydro‐2‐1H‐pyrimidone (DMPU) as the solvent, poly(methyl methacrylate (PMMA)) is obtained in the number‐average molecular weight range of 2 000 to 8 000, the molecular weight distribution being fairly narrow (ratio of weight‐ to number‐average molecular weightsM

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170603

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe thermal behaviour of thermoreversible gels prepared well below room temperature from isotactic poly(methyl methacrylate) (i‐PMMA) in butyl acetate (BAC) was investigated by means of differential scanning calorimetry. Gel‐formation and gel‐melting enthalpies together with melting enthalpy of the solvent were determined as functions of polymer concentration. The results are consistent with the existence of a polymer/solvent complex with a stoichiometry of 1,5–2 BAC molecules per i‐PMMA monom

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170604

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractVinyl ether‐terminated telechelic poly(tetrahydrofuran) (poly(THF)) was synthesized by the reaction of a bifunctional living cationic polymer of THF with an excess of Na⊕⊖OCH2CH2OCHCH2in THF at 0°C. The obtained polymer has narrow molecular weight distribution and end functionality

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170605

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractAlkyl methacrylate monomers with three kinds of dendritic fragments as alkyl groups, two kinds of Fréchet‐type and a new type with 3,5‐diphenoxybenzyl as first generation, were prepared by reaction of the corresponding dendritic bromides with methacrylic acid in good yield and were homopolymerized with a radical initiator. Polymers with side groups in first generation had a degree of polymerization (P̄n) of 17–24, markedly higher than those with side groups in second generation,P

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170606

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA side‐by‐side diffusion cell was used to study the permeability of glucose through a temperature‐ and pH‐sensitive poly(N‐isopropylacrylamide‐co‐methacrylic acid) hydrogel membrane. At fixed temperature (37°C), lowering pH in one side of the cell induced hydrogel volume collapse and strongly attenuated glucose permeation across the membrane. Hysteresis was observed in the glucose permeability versus pH

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170607

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractThe technique of photoinitiated free‐radical cyclopolymerization has been used to produce a variety of novel side‐chain liquid‐crystalline (SCLC) polymers in which an alicyclic ring structure is incorporated into a polymer backbone. Most of the SCLC polymers gave glass transition temperatures (Tg) around room temperature and clearing points around 60–70°C. However, the poly(1,5‐hexadiene) was the exception to this, exhibiting aTgvalue of 14.5°C and a clearing point of 132.5°C. Confirmation of the structure of the alicyclic ring along the polymer backbone is extremely difficult to obtain, but evidence is given in the paper to support the ri

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170608

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractA highly active rare earth coordination catalyst composed of neodymium acetylacetonate, dibutylmagnesium, and hexamethylphosphoramide (mole ratio 1:7:14) for the polymerization ofN‐phenylmaleimide (N‐PMI) was developed. The resulting poly(N‐PMI) has high molecular weight (M̄n= 9.0 × 104) and shows excellent thermal st

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170609

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY

摘要:

AbstractBulk polymerizations of methyl methacrylate (MMA) at 60°C initiated with 2,2′‐azoisobutyronitrile are influenced by the presence of an organic π‐donor such as tetrathiafulvalene (TTF). Upon addition of TTF, the ratio of weight‐ to number‐average molecular weightsM̄w/M̄nare significantly reduced and the thermal stability of the poly(methyl methacrylate) samples is increased. Kinetic investigations indicate that TTF acts as a retarder on the polymerizat

ISSN:1022-1336    

DOI:10.1002/marc.1996.030170610

出版商:Hüthig&Wepf Verlag    

年代:1996

数据来源: WILEY