Dehydrochlorination of vinylidene chloride-vinyl chloride copolymer by aqueous sodium or potassium hydroxide solutions under two-phase conditions

The reaction of solid copolymer of vinylidene chloride and vinyl chloride with aqueous sodium or potassium hydroxide solutions in the presence of quaternary ammonium or phosphonium salts as phase transfer catalysts gave dehydrochlorinated products with chlorine-substituted polyene structure. Among the catalysts used tetrapropylammonium bromide was the best and potassium hydroxide was more active than sodium hydroxide. The activity of quaternary ammonium salts was discussed in terms of hydrophile–lipophile balance. The effects of temperature and the concentration of the bases and catalysts were investigated to obtain the optimum reaction condition. Treatment of the polymer films and solutions in tetrahydrofuran with aqueous bases under two-phase conditions also produced dehydrochlorinated films and powders.     

A Grafting Study on Partially Dehydrochlorinated Poly(vinyl chloride) by Atom Transfer Radical Polymerization

HCl elimination in low ratio was first carried out from poly(vinyl chloride) to increase allylic chlorines. Partially dehydrochlorinated poly(vinyl chloride), having a macroinitiator effect, was grafted with tert‐butyl methacrylate via atom transfer radical polymerization in the presence of CuBr/2,2′‐bipyridine at 64°C in tetrahydrofuran. Original poly(vinyl chloride) was also grafted with tert‐butyl methacrylate under the same conditions to compare with that of partially dehydrochlorinated poly(vinyl chloride). The graft copolymers were characterized by elemental analysis, FTIR, ¹H and ¹³C‐NMR, differential scanning calorimetry, and gel permeation chromatography (GPC). Thermal stabilities of the graft copolymers were investigated by thermogravimetric analysis as compared with those of the macroinitiators.     

Photo-Oxidative Degradation of Poly(vinyl Chloride) Based Nanocomposites Under Ultraviolet Irradiation

The poly(vinyl chloride) based nanocomposites with 3.0% weight content of the photo-active zinc oxide (ZnO) nanoparticles or the photo-inert calcium carbonate (CaCO₃) nanoparticles was prepared by the solution mixing method, respectively. Their photo-oxidative degradation under ultraviolet irradiation (365 nm) at room temperature were compared with the pure poly(vinyl chloride) via Fourier transform infrared spectroscopy, Thermogravimetric analysis and x-ray photoelectron spectroscopy analyses. The results showed that the photo-inert calcium carbonate (CaCO₃) nanoparticles hampered the photo-degradation of poly(vinyl chloride), whereas the photoactive zinc oxide (ZnO) nanoparticles accelerated the photodegradation of poly(vinyl chloride). Furthermore, the ZnO nanoparticles also favored the crosslinking reaction of the dehydrochlorinated poly(vinyl chloride).     

Synthesis of polyesters having quaternary ammonium groups in the side chains and preparation of their blends with poly(vinyl alcohol)

Triethyl-2,3-propanediolammonium chloride (TPC) was prepared and used for the preparation of polyester and copolyesters having quaternary ammonium groups in the side chains. The polycondensation of isophthaloyl dichloride with TPC and other dihydroxy compounds was performed by the organic phase/organic phase interfacial polycondensation method using N,N-dimethylacetamide/n-heptane or trimethyl phosphate/n-heptane as reaction media in the presence of tetramethyl ethylenediamine. Blend films were prepared from these polyesters and poly(vinyl alcohol) by casting from aqueous or aqueous NaOH solution. The electrical conductivity of the blend films is remarkably affected by the moisture content and in the order of 10^?5 ～ 10^?8 S/cm in the presence of moisture. © 1994 John Wiley & Sons, Inc.     

Reaction of poly(vinyl chloride) with magnesium and grignard reagents

Reaction of poly(vinyl chloride) with magnesium under various conditions was attempted, but poly(vinyl chloride) did not react with magnesium. The reactions of poly(vinyl chloride) with benzylmagnesium chloride and allylmagnesium chloride as Grignard reagents were carried out in tetrahydrofuran at reflux temperature. It was found that the chlorine atoms in the poly(vinyl chloride) were replaced by benzyl and allyl groups by the coupling reaction, and a small amount of Grignard reagent of poly(vinyl chloride) was formed by the magnesium–halogen exchange reaction. The extent of the substitution increased with increasing reaction time and concentration of the Grignard reagent.     

纳米二氧化硅粒子对聚氯乙烯膜的表面结构及浸润性能的调控作用

报道了一种简便的调控聚合物材料表面结构及浸润性能的方法.利用流延成膜和纳米二氧化硅粒子的印迹修饰作用,制备出3种具有不同表面结构的聚氯乙烯(PVC)膜,膜的浸润性能表现为与水的接触角从103°的疏水性变为65°的亲水性,再改变至130°的疏水性.扫描电镜结果表明印迹修饰后的PVC膜具有纳米和微米尺寸的凹凸表面结构.通过对比实验证实了溶剂氯仿和NaOH溶液并不影响膜表面的疏水性能.     

Reaction of n-butyllithium with poly(vinyl chloride)

The reactions of poly(vinyl chloride) and butyllithium in tetrahydrofuran were investigated. A deep purple color developed at first with addition of butyllithium to the THF–PVC solution, and a spontaneous color change of the misture occurred successively to blue, green, and finally pale vellow. In these reaction stages, the PVC might be butylated, dehydrochlorinated, and partially lithiated by BuLi. These facts were substantiated by the results of successive reactions with various substances such as Michler's ketone, carbon dioxide, and styrene.     

Photodehydrochlorination of carbon monoxide–vinyl chloride copolymer

In order to examine effect of the carbonyl group in carbon monoxide–vinyl chloride copolymer, poly(CO–VC), photoirradiation with a high-pressure mercury lamp on the copolymer was carried out. Poly(CO–VC) had a rate of dehydrochlorination three times that of PVC, and the reaction involved a decrease in chlorine content. Also there was a marked change in the ultraviolet spectra of the photoirradiated films. However, no pronounced change of molecular weight was observed, but a change in R_f in TLC was observed clearly. These facts confirmed that photoirradiation of poly(CO–VC) produced a structural change by dehydrochlorination without serious decrease of molecular weight. In addition, photodehydrochlorination of the copolymer or PVC film was followed kinetically, and after ozonolysis of the dehydrochlorinated polymers, the number-average molecular weights were measured. From the results of degree of dehydrochlorination and molecular weight, the number average of conjugated double bonds or carbonyl groups was estimated. A mechanism for dehydrochlorination process by photo-irradiation is suggested.     

Syntheses of polymerizable viologens bearing a terminal vinyl group

Viologens that bore a terminal vinyl group were synthesized by four sequences of reactions: (1) N-vinylbenzyl-N′-n-propyl-4,4′-bipyridinium bromide chloride (V) was synthesized by the reaction of 4-(4′-pyrodyl)-N-n-propyl pyridinium bromide (III) with vinylbenzyl chloride; (2) N-β-acrylamidoethyl-N′-n-propyl-4,4′-bipyridinium dibromide (IX) was synthesized by the Menschutkin reaction of III with 2-aminoethyl bromide hydrobromide and subsequent reaction with acryloyl chloride; (3) N-β-methacryloyloxyethyl-N′-n-propyl-4,4′-bipyridinium dibromide and its analogs (XI) were synthesized by the reactions of III with the corresponding acyloxyalkyl bromides; and (4) N-vinyloxycarbonylmethyl-N′-n-propyl-4,4′-bipyridinium bromide chloride (XIII) was synthesized by the reaction of III with vinyl chloroacetate. With the exception of monomer XIII in which hydrolysis in large extent was observed during attempted polymerization, the synthesized monomers polymerized smoothly in aqueous solutions by a conventional radical procedure. Comparisons of the absorption peaks of the radical cations produced by reductions in aqueous solutions with those produced in films by ultraviolet (UV) irradiation indicate that the radical cations of polymers are associated intramolecularly in aqueous solutions.     

Adsorption of poly(vinyl alcohol) from water to a hydrophobic surface: effects of molecular weight, degree of hydrolysis, salt, and temperature

The adsorption of poly(vinyl alcohol) (PVOH) from aqueous solutions to a silicon-supported fluoroalkyl monolayer is described. Thickness, wettability, and roughness of adsorbed films are studied as a function of polymer molecular weight, degree of hydrolysis (from the precursor, poly(vinyl acetate)), polymer concentration, salt type and concentration, and temperature. The data suggest a two-stage process for adsorption of the polymer: physisorption due to a hydrophobic effect (decrease in interfacial free energy) and subsequent stabilization of the adsorbed layer due to crystallization of the polymer. Adsorption of lower-molecular-weight polymers results in thicker films than those prepared with a higher molecular weight; this is ascribed to better crystallization of more mobile short chains. Higher contents of unhydrolyzed acetate groups on the poly(vinyl alcohol) chain lead to thicker adsorbed films. Residual acetate groups partition to the outermost surface of the films and determine wettability. Salts, including sodium chloride and sodium sulfate, promote adsorption, which results in thicker films; at the same time, their presence over a wide concentration range leads to formation of rough coatings. Sodium thiocyanate has little effect on PVOH adsorption, only slightly reducing the thickness in a 2 M salt solution. Increased temperature promotes adsorption in the presence of salt, but has little effect on salt-free solutions. Evidently, higher temperatures favor adsorption but cause crystallization to be less thermodynamically favorable. These competing effects result in the smoothest coatings being formed in an intermediate temperature range.     

IR laser ablation of poly(vinyl chloride): Formation of monomer and deposition of nanofibres of chlorinated polyhydrocarbon

IR laser-induced ablation of poly(vinyl chloride) was examined under different irradiation conditions and its volatile and solid products were characterized by mass, infrared, UV and X-ray photoelectron spectroscopy, electron microscopy and thermogravimetry. It is demonstrated that the major component among the volatile products is monomeric vinyl chloride and that the process causes deposition of Cl-containing polymeric films. The proportion between the volatile and solid products as well as the nature of the deposited films at different laser fluences have been examined. We show that the deposited films incorporate less Cl atoms than poly(vinyl chloride) and that they initially contain conjugated CC bonds and incorporate nano-sized fibre and necklace features. The process represents the first example of thermal degradation of poly(vinyl chloride) into monomer and makes it possible to fabricate crosslinked Cl-containing intractable polymer films.     

Merrifield-like resin beads by acid catalyzed incorporation of benzyl chloride into dehydrochlorinated PVC

A method is presented for preparing Merrifield-like resin beads starting from poly (vinyl chloride) (PVC) in spherical bead form. In this method, first, PVC is partially dehydrochlorinated in boiling methanolic KOH (20%) solution to create minute amounts of allylic carbon centers. Those centers trigger the un-zipping process and make further dehydrochlorination possible at relatively low temperatures (180-200 °C), while retaining the bead shapes. Acid catalyzed reaction of the dehydrochlorinated PVC particles with benzyl chloride at 180 °C yields crosslinked spherical bead polymers possessing chloromethyl benzene functions as high as 3.4 mmol g⁻¹. Experiments showed that, high yields of benzyl chloride insertions can be attained by using PVC samples with 40-50% of unsaturations. In the study transformation yields in each step were followed by conventional analytical methods and IR spectrometry. It was also demonstrated that modification of the chloromethyl groups either with KCN or sodium acetate proceeds with nearly quantitative yields, as in the case for chloromethylated styrene-divinyl benzene resins.     

Effect of Chemical Structure and Charge Distribution on Behavior of Polyzwitterions in Solution

Summary: The hydrodynamic and conformational properties of polyelectrolyte poly(N,N-diallyl-N,N-dimethylammonium chloride) and its corresponding polybetaine poly(2-diallyl(methyl)ammonio)acetate) molecules in aqueous solutions with various ionic strength and pH, were studied by viscometry, static and dynamic light scattering methods. It was established that a 1 M NaCl solution is a thermodynamically good solvent for poly(N,N-diallyl-N,N-dimethylammonium chloride). In water solutions conformation of poly(2-diallyl(methyl)ammonio)acetate) molecules corresponds to polymer coil under θ–conditions. An increase in the concentration of NaCl in water and 0.1M NaOH solutions from 0 to 1 mol/l brings about a sharp gain in the intrinsic viscosity of the polymer and in the hydrodynamic radius of molecules. This effect results from the decomposition of zwitterion pairs responsible for the compact conformation of polymer molecules in water and 0.1 M NaOH. The Kuhn segment length for poly(2-diallyl(methyl)ammonio)acetate) molecules A = 6.3 nm determined in water and in 0.1 M NaOH solutions practically coincided with A value 6.6 nm, received in 1 M NaCl and in 0.1 M NaOH/1M NaCl. For poly(N,N-diallyl-N,N-dimethylammonium chloride) molecules in 1 M NaCl solutions A = 3.9 nm.     

聚氯乙烯-丙烯酸丁酯接枝共聚物的结构表征

以通用聚氯乙烯(PVC)和脱氯化氢PVC树脂为基体,采用悬浮溶胀接枝共聚法合成聚氯乙烯-丙烯酸丁酯接枝共聚物,对脱氯化氢PVC和接枝共聚物的结构进行了表征.结果表明,以碱液为介质加热PVC能脱除少量氯化氢,得到以链节数为2,3,4的共轭双键为主的不饱和结构,而树脂的分子量变化不大;在相同接枝反应条件下,采用脱氯化氢PVC与丙烯酸丁酯接枝共聚可以提高接枝率和接枝效率;PVC接枝共聚物的特性粘度随接枝率增加而增加,其重均分子量和分子量分布指数均大于接枝所用的PVC树脂.     

Novel semi‐IPN through vinyl silane polymerization and crosslinking within PVC films

Novel semi‐IPN (interpenetrating polymer networks) were synthesized through vinyl silane modification of unplasticized poly(vinyl chloride) (PVC) films using relatively low temperatures, relatively high vinyl silane contents, and several different processing routes. A free‐radical initiator was used to promote reaction of the vinyl groups, and an aqueous acetic acid solution was used to promote the methoxysilane hydrolysis and condensation (HC) reactions for siloxane crosslink formation. A gel consisting of silane alone was formed prior to the HC process, indicating the formation of a semi‐IPN. The gel content following the HC process far exceeded the silane content, indicating a significant amount of PVC was entrapped by the silane network. This conclusion is supported by the homogeneous molecular structure and morphology of the films. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 8–22, 2001     

Dechlorination behaviour of flexible poly(vinyl chloride) in NaOH/EG solution

Flexible poly(vinyl chloride) (PVC) was found to be dechlorinated in NaOH/ethylene glycol (EG) solution at moderate temperature and at atmospheric pressure. The degree of dechlorination increased over time with all particle sizes and with decreasing particle size. Decreased particle size resulted in an increased effective surface area, increasing the contact between the material and OH⁻ in the NaOH/EG solution, which contributed to the high degree of dechlorination. The dechlorination of flexible PVC in NaOH/EG solution was expressed as a first-order reaction and proceeded under chemical reaction control. Diisononyl-phthalate (DINP) in the flexible PVC powder decomposed readily into phthalic acid and isononyl alcohol in a short time. For the dechlorination of the flexible PVC, the substitution (S_N2) of chloride by the hydroxyl group was considered to be preferential to the elimination (E2) of hydrogen chloride.     

IR laser-induced decomposition of poly(vinyl chloride-co-vinyl acetate): Control of products by irradiation conditions

IR laser-induced, ablative decomposition of poly(vinyl chloride-co-vinyl acetate) was examined under different irradiation conditions and its volatile and solid products were characterized by mass spectroscopy, infrared spectroscopy, Raman spectroscopy and UV spectroscopy and EDX-measurements. The laser decomposition of the copolymer, compared with that of poly(vinyl acetate) and poly(vinyl chloride), is revealed to be a more efficient process leading to solid films with the proportion of Cl- and CH₃C(O)O-groups controlled by irradiation conditions.     

Transparent,Electrically Conductive Composites Derived from Polypyrrole and Poly[Vinyl Chloride) by Vapor-Phase Polymerization: Effect of Environment on Polymerization and Reaction Mechanism

Abstract

Transparent, electrically conductive composite films were obtained by vapor-phase polymerization of pyrrole into a poly(vinyl chloride) (PVC) matrix containing FeCl₃. The effects of water and of organic solvents on the polymerization were investigated. It was found that the conductance of the films increases in the presence of both water vapor and of good solvents or swelling agents for PVC. The conductivity of the films rises with reaction time and so does the rate of increase with higher FeCl₃ concentration. The production of HCl was monitored by two methods, the precipitation of AgCl in an aqueous solution of silver nitrate and the increase in conductance of an aliquot of distilled water which had been placed into the reaction chamber. On the basis of our experimental results, we propose a reaction mechanism that explains the observed increase of conductance with time. A universal kinetic formula has been derived which relates the increase of electrical conductance to other parameters characterizing the boundary conditions of the polymerization.     

Adsorption of poly(N‐ethyl‐4‐vinyl pyridinium bromide) onto langmuir‐blodgett films built up from amphiphilic polymers

The interaction of a strong cationic polyelectrolyte, poly(N‐ethyl‐4‐vinyl pyridinium bromide), with Langmuir‐Blodgett (LB) films built up from four monolayers of amphiphilic derivatives of the alternating copolymers of maleic acid and alkenes (one of the monolayers was formed by the amphiphilic copolymer containing pyrenyl groups as fluorescent labels) was examined. Transformations of absorbance spectra and quenching of fluorescence of the LB films were detected after their contact with aqueous solutions of the cationic polyelectrolyte. These changes were attributed to the adsorption of poly(N‐ethyl‐4‐vinyl pyridinium bromide) onto such films. The efficiency of this process was found to be rather sensitive to the variations in pH of the surrounding medium: adsorption of the cationic polyelectrolyte onto the LB films was pronounced in basic media while it became rather weak in acidic media.     

Impedance spectroscopy of chitosan/poly(vinyl alcohol) films

Journal of Solid State Electrochemistry - Polymer films were cast from aqueous solutions of chitosan (CS) and poly(vinyl alcohol) (PVA) in employing tetraethoxysilane (TEOS) as a crosslinking...