摘要:

AbstractPoly[1‐(2‐oxazoline‐2‐yl)ethylene] (2a), poly[1‐(5‐methyl‐2‐oxazoline‐2‐yl)ethylene] (2b), poly[1‐(4,4‐dimethyl‐2‐oxazoline‐2‐yl)ethylene] (2c), poly[1‐(4,4‐dimethyl‐5,6‐dihydro‐4H‐1,3‐oxazine‐2‐yl)ethylene] (2d), and poly[1‐(4,4,6‐trimethyl‐5,6‐dihydro‐4H‐1,3‐oxazine‐2‐yl)ethylene] (2e) were synthesized with high yields by radical polymerization, using AIBN as initiator. Polymer2awas found to be soluble in water and in organic solvents such as methanol, acetone, chloroform and benzene, polymer2bin hot water and in the same organic solvents, and polymers2cand2dare insoluble in cold and hot water. However, polymers2dand2eare soluble in diethyl ether and hexane. Addition reactions of polymers2a–ewith carboxylic acids and thiols were investigated. Reactions of polymer2awith acetic acid, benzoic acid and cinnamic acid at 110°C for 10 h proceeded with 57–74 mol‐% conversion in DMF, NMP and DMSO, and reactions with benzenethiol and thiobenzoic acid quantitatively under the same reactions conditions. Reactions of polymers2band2cwith carboxylic acids proceeded with 4–36 mol‐% conversion, and with benzenethiol and thiobenzoic acid with 80–96 mol‐% conversion. From the results the following order of reactivities of these polymers may be suggested:2a ≃ 2d>2e>2b>2c. According to their higher nucleophilicity, the reactivities of benzenethiol and thiobenzoic acid

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860401

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractPoly(vinyl acetate)/poly(dimethylsiloxane) graft copolymer (4a), with a controlled poly(dimethylsiloxane) graft chain length, was synthesized by radical copolymerization of vinyl acetate with poly(dimethylsiloxane) (3) having a dimethylvinylsilyl end group.3was prepared by living anionic polymerization of hexamethylcyclotrisiloxane (1) with butyllithium and subsequent termination with chlorodimethylvinylsilane (2). Poly(vinyl alcohol)/poly(dimethylsiloxane) graft copolymer (4b) was then synthesized by selective saponification of the poly(vinyl acetate) segments in the graft copolymer4awith K2CO3in methanol.

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860402

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe chemical dehydrochlorination of poly(vinyl chloride) was studied in solution in tetrahydrofuran. Two materials, a mass polymer of 55% syndiotacticity and a low temperature polymer of 63% syndiotacticity, were dehydrochlorinated with potassium hydroxide and with potassiumtert‐butoxide. The dehydrochlorination products were characterised by their chlorine contents and by UV/visible, IR and Raman spectroscopy, as a function of reaction time. The course of the reaction was found to be substantially independent of tacticity and the dehydrochlorinating reagent. Initially, the reaction follows a similar path to that occurring during photo‐ and thermal degradation, but as the dehydrochlorination continues, longer conjugated polyenes are formed than by these two latter processes. Sequences of 60 double bonds occur at the dehydrochlorination levels of about 55% that are attained after reaction times of 24 h. These sequences are sterically protected from cross‐linking reactions by the presence of longish sequences of unreacted CHClC

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860403

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe chemical dehydrochlorination of poly(vinyl chloride) was studied in solution inN,N‐dimethylformamide. By comparison with solutions in tetrahydrofuran, examined previously, the reaction was found to occur at a significantly enhanced rate for the four systems studied, a mass polymer of 55% syndiotacticity and a low temperature polymer of 63% syndiotacticity, dehydrochlorinated with potassium hydroxide or with potassiumtert‐butoxide. Furthermore, at dehydrochlorination levels up to about 60%, markedly longer polyene sequences are formed, the more so in the case of potassiumtert‐butoxide., where they reach values of at least 65, as assessed by Raman spectroscopy. For levels of 80%, and greater, there is a significant decrease in the sequence lengths, the result of cross‐linking, which is facilitated by the substantial loss of the\documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--} ({\rm CHCl \hbox{---} CH}_{\rm 2} \rlap{--} )_n$\end{document}sequences that sterically protect the long polyenes in the les heavily dehydrochlorinated materials. Limited results are also presented for chemically dehydrochlorinated PVC prepared by the urea clathrate method; the insolubility of this polymer probably leads to degradation on the surface of the particl

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860404

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractRaman and infrared spectroscopic studies on the chemical degradation products of two vinyl chloride/vinyl acetate copolymers and a vinyl chloride/vinyl acetate/vinyl alcohol terpolymer, obtained with the system potassiumtert‐butoxide/N,N‐dimethylformamide, show that substantially complete dehydrochlorination occurs. Although the vinyl acetate groups are hydrolysed to the corresponding alcohol these latter largely remain intact and block the extension of the polyene sequences, whose lengths, measured by Raman spectroscopy, are in agreement with values calculated from the initial polymer composition. No degradation other than hydrolysis occurs with vinyl acetate and vinyl alcohol homopolymers or a vinyl alcohol/vinyl acetate copolymer. The thermal degradation of the copolymers containing vinyl chloride, and of two vinyl chloride homopolymers of differing syndiotacticity, at 153°C inN,N‐dimethylformamide, gives both dehydrochlorination and elimination of the comonomer units, the latter reaction occurring at least as rapidly as the former. A crosslinked structure, in which there is some steric stabilisation and, hence, conjugated polyene sequence lengths up to about 40, is formed. A maximum sequence length of 8 is found in thermally degraded poly(vinyl acetate), but the conjugated polyenes are too short to be detected in degraded poly(vinyl alcohol) and the vinyl alcohol/vinyl acetate cop

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860405

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA block copolymer (6) with both hydrophilic and hydrophobic regions was synthesized, in order to examine its interaction with model membranes and its uptake by living cells. The copolymer comprised poly(ethylene oxide) and poly(L‐lysine) with 50 mol‐% substitution of the ε‐amino groups with palmitoyl groups. To permit125I‐labelling,p‐methoxyphenyl residues (1–4 mol‐%) were incorporated into the block copolymer and into a poly(ethylene oxide) used for comparison. Sudan Red 7Bsolubilization studies indicated that the block copolymer, but not the homopolymer, forms micelles. Differential scanning calorimetry of dipalmitoyl‐phosphatidylcholine liposomes indicated that the block copolymer interacts with and probably penetrates lipid membranes. Both poly(ethylene oxide) and the block copolymer were captured by rat peritoneal macrophages in vitro, and inhibitor studies indicated that uptake of both polymers was by pinocytosis. Rates of uptake were indicative of adsorptive pinocytosis, and it is concluded that both poly(ethylene oxide) and the block copolymer present a largely hydrophilic aspect which interacts positively with

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860406

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA new Continuous Polymer Fractionation method, called CPF, is described. The polymer to be fractionated is dissolved in a solvent/non‐solvent mixture, and this solution (feed) is extracted continuously by a second liquid (extracting agent), which contains the same solvent components as the feed. In the case of PVC, the fractionation was carried out with a pulsed counter current extraction apparatus and THF/water was used as solvent/non‐solvent mixture. Fractionation is achieved by the fact that the molecules are distributed over the counter current phases according to their chain length; the feed leaves the column as gel and the extracting agent as sol. First some explorative experiments were made in order to determine suitable working parameters, like frequency and amplitude of pulsation, compositions of feed and extracting agent and the ratio of flow. With the so obtained parameters, preparative experiments were carried out, yielding five PVC‐fractions with molecular weights ranging from 20 000 to 100 000 (GPC, LS) and non‐uniformities,U= (Mw/Mn) −1, of about 0,2 (GPC) using a starting material withMw= 67 000 a

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860407

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractInvestigations with ca. 100 organic liquids in a temperature range from −20°C to 90°C result in a survey of the solubility behaviour of PVC. The experimental results were compared with the predictions of the solubility parameter theory: Accepting δ = 9,75 (cal/cm3)1/2as the solubility parameter for PVC, all solvents (except ketones in which PVC is soluble independent of their solubility parameters) are located within the range of δPVC± 0,75. Only three of the 100 liquids examined turned out to be (endothermal) theta‐solvents, namely the aromatic solventso‐xylene, phenetole and dimethyl phthalate. The theta‐temperatures ino‐xylene and phenetole were determined viscometrically by means of the temperature dependence of the Mark‐Houwink exponent to be 84 and 88°C, respectively. Viscosity measurements were also performed in the temperature range of 25 to 60°C with solutions of PVC 75 000 in 10 thermodynamically good solvents used for rheological investigations. In all cases the intrinsic viscosities decrease slightly with increasing temperature, i.e., all solutions are weakly exothermal. The binary cluster integral, β, was determined (taking the monomeric unit as the statistical segment) and the polar contribution, βe, was calculated from Yamakawa's theory. The correlations between the non‐polar part of (βn= β – βe) and the solubility parameter of the solvent, found by Utracki, were tested and found to be valid f

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860408

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractFrom the break‐down in the viscosity and from the increase of the intensity of the scattered light, associated with the entrance into the two‐phase region, the pressure dependence of the demixing temperature of solutions of PVC 37 000, PVC 75 000 and PVC 100 000 in phenetole and PVC 75 000 ino‐xylene was measured up to 1 000 bar. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) The application of pressure increases the demixing temperatures of PVC in both solvents by about 1 K/100 bar. For a qualitative forecast of the pressure effects, the solubility parameter theory in combination with the corresponding states principle, and an empirical correlation to the relative distance of the critical demixing temperature to the melting point of the pure solvent were used. The results of both concepts are in accord with the experimental fin

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860409

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractUsing a self‐constructed light scattering apparatus, the pressure dependence of the demixing temperature of solutions of PVC 20 000, PVC 37 000 and PVC 70 000 in THE/water was determined up to 1 000 bar for different compositions of the mixed solvent. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) In contrast to the thetasolventso‐xylene and phenetole, the solubility decreases with increasing pressure for all molecular weights and compositions under investigation typically by about 1 K/100 bar. The evaluation of the experimental findings demonstrates that the volume fraction of the nonsolvent in the mixed solvent, φ 2*, is the variable that governs phase separation: For the present region ofpandT, a given polymer solution demixes at a characteristic constant value of φ 2*, no matter how it is reached. This fact allows the prediction of pressure influences from knownpVTdata of the pure components and measurements at atmospheric pressure. A qualitative theoretical understanding of the observed influences ofpandTcan be reached on the basis of the solubility paramet

ISSN:0025-116X    

DOI:10.1002/macp.1985.021860410

出版商:Hüthig&Wepf Verlag    

年代:1985

数据来源: WILEY