摘要:

AbstractThe oligomerization of oxetane (trimethylene oxide) initiated by sulfuric acid in methylene chloride in the presence of 1,3‐propanediol (trimethylene glycol) leads to the formation of α‐hydro‐ω‐hydroxyoligo(oxytrimethylene)s. The effect of adding different amounts of trimethylene glycol was studied, and the dimer, 3,3′‐oxydipropanol, could be isolated. Polymers from dimethyl terephthalate and 3,3′‐oxydipropanol and copolymers from 1,3‐propanediol, 3,3′‐oxydipropanol and dimethyl terephthalate were synthesized. The influence of the chemical structure on their thermal t

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900601

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

Abstract1,4‐Dioxanium and other trialkyloxonium ions were observed by1H NMR in the polymerization of oxirane initiated with the triphenylmethyl cation. The major product of polymerization is 1,4‐dioxane. Thus, the kinetic data for the same system previously published by other authors, refer to the propagation in which oxirane propagates with the participation of dioxanium and/or other unstrained trialkyl oxonium cations. Our present results, together with previous data of León et al., indicate that the rate constants of propagation with these two kinds of species are very close to each other. Propagation with participation of the oxiranium ion probably takes place only at the very beginning of polymeriza

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900602

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractFilms of poly(3‐phenyl‐2,5‐thienylene) (1a), poly[3‐(4‐methoxyphenyl)‐2,5‐thienylene] (1b) and poly[3‐(4‐trifluoromethylphenyl)‐2,5‐thienylene] (1c) were electrochemically prepared. The conductivities of1a,1band1cwere determined to be 140, 40, and 1,8 · 10−3S/cm, respectively. The surfaces of1aand1bare considerably rough. The infrared spectra of electrochemically neutralized polymers showed that they have a regular structure. Cyclic voltammograms showed that the oxidation potential increases in the order1b<1a<1c(in the neutral state). The results are discussed in terms of the electronic effect of the substituents. The visible spectra of these neutral polymers showed that the π‐π*‐transition occurs at lower energy than that of poly(2,5‐thienylene) (1d). This indicates that the pendant aryl groups are conjugated with the main chain. The effect of substituents on the peak positions of the π‐π*transition is hardly discernible.1ais highly anode‐active as compared with1d. The spectral change of1aupon PF 6−doping presumably is the indication of polarons at low doping levels. The changes during Et4N+

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900603

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe phosphorus‐functional iniferter,N,N′‐dimethyl‐N,N′‐bis[2‐(N‐diethoxyphosphinoyl‐N‐methylamino)ethyl]thiuram disulfide (2), was synthesized and characterized. Thermal polymerization of methyl methacrylate (MMA) and styrene in presence of this compound led to the formation of α, ω‐phosphorylated PMMA and polystyrene. The kinetics of polymerizations of MMA and styrene using this iniferter was studied at 70°C and the different parameters, related to initiation, chain transfer, and primary radical termination reactions, were evaluated. In the case of styrene the extent of primary radical termination was considerably less and mutual termination reactions were found to be absent. The telomers were analysed

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900604

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractHydrogels (crosslinked polymers with a defined water content) based onN‐vinyl‐2‐pyrrolidinone and 2‐hydroxyethyl methacrylate of different compositions were prepared by radical copolymerization and swollen in buffered isotonic sodium chloride solution. The linear expansion to hydration, weight‐percentage of hydration, refractive index, extractables, percentage of transmission of visible light and oxygen permeability of the resulting hydrogel samples were

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900605

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractThe current cellulose hydrolysis methods were applied to cellulose‐graft‐poly(vinyl acetate‐co‐methyl acrylate) giving rise to a residual solid that showed IR absorptions at 3 600 – 3 000 and 1775 cm−1and partial insolubility in the solvents of poly(vinyl acetate‐co‐methyl acrylate). Some model experiments showed that hydrolysis of the acetoxy and methoxycarbonyl groups takes place and subsequent γ‐lactonization and crosslinking in the grafted synthetic polymer, parallel to the cellulose hydrolysis. It became evident that the competition between lactonization and crosslinking and their extent are controlled by the sequence‐length distributions of the monomeric units in the copolymer and by the conversion in the hydrolysis reaction, respectively. Both esterification reactions were eliminated when the experiment was performed at sufficie

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900606

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractOptically active divinyl ethers, (−)‐(R)‐ and (+)‐(S)‐2,2′‐bis[2‐(2‐vinyloxyethoxy)ethoxy]‐3,3′‐dimethyl‐1,1′‐binaphthyl [(R)‐1band (S)‐1b] were polymerized to produce chiral poly(crown ether)s. Their optical rotation was found to be profoundly influenced by the polymerization conditions. When increasing the monomer concentration from 0,1 to 0,3 mol · 1−1, after polymerization with SnCl4in CH2Cl2at 0°C, the optical rotation of the resulting polymers is drastically changed from +44,5° to −17,3° for (R)‐1band from −35,6° to +20,9° for (S)‐1b. The analysis of1H NMR showed that the polymers have changed their optical rotation due to a configuration which has a tendency to be preferentially racemic diad at higher monomer concentrations in a nonpolar solvent. There are indications that the twist of 2,2′‐binaphtyl moieties, the methyl groups in 3‐, and 3′‐positions as steric barrier, and the intramolecular solvation of the growing carbo‐cation cooperatively cont

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900607

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractToluene, anisol, thioanisol, 4‐phenoxyacetophenone andN,N‐diacetyl‐4‐phenoxyaniline were subjected to a Friedel‐Crafts acylation with 2,6‐difluorobenzoyl chloride. The resulting 4′‐substituted 2,6‐difluorobenzophenones1a–ewere condensed with trimethyl silylated Bis‐phenol‐A (2) to yield homopolyethers with pendant functional groups. A series of copolyethers was analogously prepared by concondensation of 4′‐substituted 2,6‐difluorobenzophenones with a diphenol and 4,4′‐difluorobenzophenone (4a) or bis(4‐fluorophenyl) sulfone (4b), and another series by cocondensation of2with mixtures of 4′‐substituted 2,6‐difluorobenzophenones and 2,6‐difluorobenzonitrile (8) or 2,6‐difluoropyridine (9). All polyethers were characterized by inherent viscosities, elemental analyses and DSC‐measurements. In individual cases GPC‐measurements, thermomechanical and thermogravimetric analyses were conducted. The quantitative polymer‐analogous oxidation of methylthio groups into methylsulfinyl and

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900608

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractPolymerizations of two bicyclic acetals,rac‐2(a), 3(e)‐bis(benzyloxy)‐6,8‐dioxabicyclo‐[3.2.1]octane (1d) and theD‐enantiomer of 2(a),3(e),4(a)‐tris(benzyloxy)‐6,8‐dioxabicyclo[3.2.1]octane (1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐β‐D‐allopyranose) (1e) were investigated in dichloromethane as solvent at different temperatures ranging from −90 to −30°C. The polymerization of1dgave polyacetals containing both thetrans‐ andcis‐2,6‐linked tetrahydropyran units (2dand3d) over the entire temperature range. The proportion of3dincreased up to 73% with decreasing initial monomer concentration at higher polymerization temperature. On the other hand, the polymerization of1egave rise to polymers exclusively or predominantly composed oftransunits (2e), the content ofcisunits (3e) being at most 25%. On the basis of these results, along with the previous experimental results on the polymerizations of three other relevant bicyclic acetals (1a–c), the marked substituent effect as well as the influence of polymerization temperature and initial monomer concentration on the stereochemical course of the polymerization are discussed in terms of a propagation mechanism involving an oxonium exchange reac

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900609

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY

摘要:

AbstractBipolyamides containing mesogenic groups were prepared by solution polycondensation from aromatic dicarbonyl dichlorides and novel diamines. Ortho‐substitution and the aliphatic chain length of α,ω‐bis(4‐aminophenyl)alkylenes affected the thermal transitions of the resulting polyamides profoundly. Introduction of an ethylene unit into the stiff biphenylene segment not only reduced the isotropization temperatures, but also depressed the tendency to form liquid c

ISSN:0025-116X    

DOI:10.1002/macp.1989.021900610

出版商:Hüthig&Wepf Verlag    

年代:1989

数据来源: WILEY