摘要:

AbstractStarting fromD‐glucosamine, the synthesis of various differently modified methyl and benzyl 2,6‐diaminosaccharides11, 12, 17and18was accomplished. Interfacial and solution polycondensation of those diamino derivates with aromatic and aliphatic acyl chlorides yielded polyamides34, 35, 36and37a–dwhich were characterized by1H NMR spectroscopy and their inherent viscosities. The presence of an anomeric benzyl group in12did not decrease the reactivity of the 2‐amino function. The free hydroxy functions in polyamides35a–bwere acetylated to give polyamides39a–b. Partially blocked polyamides36a–dhad similar properties as unprotected polyamides34–35a–d. Under corresponding conditions di‐O‐acylated diaminosaccharide18gave only oligomer. Number‐average molecular weights were obtained from gel‐permeation chromatography to be 10300

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940401

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe influence of the concentration of the reactants (bis(chloromethyl) derivative, NaOH) and of the reaction time upon the intrinsic viscosity and the yield of the polymers synthesized by the heteropolycondensation of sodium azobenzene‐4,4′‐diolate with 1,4‐bis(chloromethyl)‐2,5‐dimethylbenzene is presented. The optimum conditions of polymer synthesis are

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940402

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe synthesis of low‐molecular‐weight poly(ether‐ester)s bearing hydroxyl side groups by poly‐condensation, in 1‐methyl‐2‐pyrrolidone at 105–110°C, of the potassium salts of racemic malic and (R,R)‐tartaric acids and α‐(2‐bromoethyl)‐ω‐bromopoly(oxyethylene)s of different molecular weights is described. The polymers were characterized by GPC and1H and13C NMR. The fixation of 1‐naphthylacetic acid, a plant growth regulating agent, was successfully achieved in the case of poly(ether‐ester)s deriving from tartaric acid, by carrying out the esterification reaction at room temperature in the presence ofN,N′‐dicyclohexylcarb

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940403

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe stereochemistry of propene polyinsertion catalyzed by a highly isospecific MgCl2‐supported Ziegler‐Natta system was investigated by means of the gas chromatographic/mass spectrometric (GC‐MS) characterization of the saturated oligomers (hydrooligomers) formed in the presence of H2at high pressure (as a chain transfer agent). It was shown that the hydrooligomer distribution is a true catalyst “fingerprint”, from which, in case of systems with (prevailingly) a single type of active centres, both the regio‐ and the stereospecificity of polyinsertion can be quantitativel

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940404

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractPoly(aspartic acids) of different chain lengths (11, 14, 18, 24, 30, 52, 58, ≈ 115) were prepared, for the use in aminoglycoside‐induced nephrotoxicity inhibition studies, some in their pureL‐ orD‐configuration and in pure α‐linkage form by the polymerization of α‐amino acidN‐carboxyanhydride (NCA) derivatives with a variety of dialkyl aspartate molecules as primary amine initiators. The primary amine chosen served as an internal reference in the1H NMR spectrum for the estimation of the degree of polymerization (chain length) in these molecules. Poly(aspartic acids) with varying amounts ofDandLasymmetric centres and in pure α‐linkage from were also prepared. Poly[(α‐co‐β)(L‐co‐D) aspartic acid] was prepared by a simplified thermal polymerization procedure for biological studies and also to study the tacticity effects in its13C NMR spectrum. A qualitative correlation was demonstrated between the retention times from gel‐permeation chromatographic analysis and the1H NMR method used to est

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940405

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractSignificant drift in the compositions of copolymer and of unreacted monomer mixture is predicted to occur during the bulk copolymerization ofN‐vinyl‐2‐pyrrolidone (VP) with butyl acrylate (BA), when the inital feed mixture contains 75 wt.‐% VP. The drift in copolymer composition has been confirmed by 1 the optical appearance and glass transition (Tg) behaviour of the products of the γ‐ray initiated copolymerization at various fractional conversions (C) and 2 theTgbehaviour of low‐conversion samples of poly(VP‐co‐BA) blended in propertions so as to simulate the overall composition of material that would be present cumulatively at selected values ofCduring an actual copolymerization. The compositions of unreacted monomer mixtures co‐existing with copolymer at selected conversions have been calculated and intrinsic viscosities [η] of blends dissolved in these VP/BA mixtures have been measured. Theta conditions for the blends have been established turbidimetrically in chloroform/heptane and the corresponding values of [η]Θmeasured. The chain expansion factors thereby derived from [η] and [η]Θshow a decreasing affinity of copolymer for residual monomer during the co

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940406

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractPoly(2‐methoxy‐1,4‐phenylenevinylene) (PMVP) and copolymers containing both unsubstituted (1,4‐phenylenevinylene, PV) and 2‐methoxy‐1,4‐phenylenevinylene (MPV) units were prepared in thin films from their water‐soluble sulfonium salt precursor polymers. Drawn films (L/L0= 6) of the PMPV homopolymer could be doped with I2vapor and FeCl3to give conductivities of 3,2 and 4,0 ċ cm−1, respectively. The conductivity of FeCl3‐doped copolymer films ranged from 100to ca. 102ċ cm−1depending on the composition. The third‐order nonlinear susceptibility, χ(3), for the PMPV film was investigated by degenerate four‐wave mixing technique using 400 femtosecond pulses at 602 nm. A relatively large χ(3)value (7,9 ċ 10−10esu) with a sub

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940407

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA new route of synthesis of liquid‐crystalline polymethacrylates was investigated. The synthetic route involved side‐group liquid‐crystalline polymethacrylates (LCPMA) with a turned ester group between the aromatic rings in the central unit of mesogens (2) as compared with the usual LCPMA (1). For a series of compounds of this type the liquid‐crystalline properties were investigated using differential scanning calorimetry, polarizing microscopy and X‐ray diffraction techniques. Generally stable smectic phases were found for these isomeric LCPMA. The described synthetic route opens possibilities to form new polymers from a wide field

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940408

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractAnodic coupling in CH3CN + 0,1 M tetraethylammonium perchlorate of some 2,2′‐bipyrrolyl monomers bridged byXgroups at theN,N′‐positions (X= CHCH (1),o‐C6H4(2) CH2 (3), (CH2)2 (4) and (CH2)3 (5)) produces conducting, α‐coupled polypyrroles (from IR spectroscopy), containing 0,25–0,30 counteranions per pyrrole ring (from elemental analysis). The in‐situ conductivity spans from values commonly found forN‐substituted polypyrroles (4 ċ 10−3S/cm for5) to unusually high values (2,5 S/cm for4). A linear correlation between redox potentials and log of conductivities of the polymers evidences the influence of the polymer el

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940409

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractDielectric spectroscopy in the microwave regime (106–1010Hz) is employed to study the molecular dynamics of a set of ferroelectric liquid‐crystalline side group polymers with variable spacer length and different molecular weight, and on their low‐molecular‐weight counter‐part. One relaxation process is observed, the β‐relaxation, which is assigned to the hindered rotation of the mesogens around their long molecular axis. This librational process is nearly uninfluenced by the molecular weight and depends only slightly on the spacer length. At the smectic‐smectic phase transition SA/SC*the β‐relaxation does not decrease in its relaxation strength and shows no slowing down of its relaxation rate. This is in pronounced contrast to the common explanation of the origin of ferroelectricity in liquid crystals and requires a n

ISSN:0025-116X    

DOI:10.1002/macp.1993.021940410

出版商:Hüthig&Wepf Verlag    

年代:1993

数据来源: WILEY