Chain transfer for vinyl monomers polymerized in N-allylstearamide

Apparent transfer constants have been determined for styrene, methyl methacrylate vinyl acetate, and diethyl maleate polymerized in N-allylstearamide at 90°C. Regression coefficients for transfer were: methyl methacrylate, 0.301 × 10^?3; styrene, with no added initiator, 0.582 × 10^?3; styrene, initiated with benzoyl peroxide, 0.830 × 10^?3; vinyl acetate, 62.01 × 10^?3; and diethyl maleate, 2.24 × 10^?3. Rates of polymerization were retarded for both styrene and methyl methacrylate. Vinyl monomer and comonomer disappearance followed an increasing exponential dependence on both initiator and monomer concentration. Although degradative chain transfer probably caused most of the retardation, the cross-termination effect was not eliminated as a contribution factor. Rates for the vinyl acetate copolymerization were somewhat retarded, even though initiator consumption was large because of induced decomposition. The kinetic and transfer data indicated that the reactive monomers added radicals readily, but that rates were lowered by degradative chain transfer. Growing chains were terminated at only moderate rates of transfer. Unreactive monomers added radicals less easily, producing reactive radicals, which transferred rapidly, so that molecular weights were lowered precipitously. Although induced initiator decomposition occurred, rates were still retarded by degradative chain transfer. A simple empirical relation was found between the reciprocal number-average degree of polymerization, 1/X?_n1 and the mole fraction of allylic comonomer entering the copolymer F₂, which permitted estimation of the molecular weight of copolymers of vinyl monomers with allylic comonomers. This equation should be applicable when monomer transfer constants for each homopolymer are known and when osmometric molecular weights of one or two copolymers of low allylic content have been determined.     

Synthesis and properties of amphiphilic vinyl acetate triblock copolymers prepared by copper mediated living radical polymerisation

Polymerisation of vinyl acetate by conventional free radical polymerisation using a diazo initiator followed by copper mediated living radical polymerisation with a range of monomers was studied. This method led to the synthesis of triblock copolymers. We have thus successfully prepared several new ABA triblock copolymers where B is poly(vinyl acetate) and A is (dimethylamino)ethyl methacrylate (DMAEMA), (polyethylene glycol) methyl ether methacrylate (MeO(PEG)MA) or solketal methacrylate (SMA). The sequential conventional/living radical polymerisation approach provided an efficient route to synthesis of new block copolymers. The properties of these amphiphilic polymers have been subsequently investigated by ¹H NMR, fluorescence spectroscopy, tensiometry and dynamic light scattering to investigate their behaviour as potential surfactants.     

Synthesis of ethylene copolymers

Summary Copolymers of ethylene with styrene, methyl methacrylate, acrylonitrile, and vinyl acetate were prepared by reaction in toluene in presence of tributylborine as polymerization catalyst.     

丁烯二酸三乙基锡酯的共聚

合成了顺-及反-丁烯二酸三乙基锡酯,并研究了它们和苯乙烯及甲基丙烯酸甲酯的共聚合反应。两种锡酯都能与苯乙烯共聚,与甲基丙烯酸甲酯未能得到共聚物。     

The thermal degradation of copolymers of vinyl acetate with methyl methacrylate and other monomers

The thermal degradation of copolymers of vinyl acetate with methyl methacrylate, styrene and ethylene has been investigated using thermal volatilization analysis and thermogravimetry, together with analysis of volatile and involatile degradation products. All three copolymer systems show some of the features characteristic of the homopolymers of the monomers concerned. There is evidence, however, for an intramolecular lactonization process in VA—MMA copolymers, involving reaction of adjacent VA and MMA units with elimination of methyl acetate. This reaction occurs less readily than the analogous process in vinyl chloride—MMA copolymers. Mechanisms of the various degradation reactions are discussed.     

顺丁烯二酸烷基有机锡的研究Ⅰ.顺丁烯二酸烷基三丁基锡酯的合成及其共聚反应

本文合成了顺丁烯二酸甲基三丁基锡酯(MTBTM)和顺丁烯二酸乙基三丁基锡酯(ETBTM),并利用该单体分别与VAc和St进行共聚反应,着重从聚合温度、单体浓度、聚合溶剂等条件探讨其共聚规律,发现在一定条件下,MTBTM和VAc共聚,转化率可达到88%。用红外光谱、¹H-NMR和元素分析等方法对共聚物结构和组成进行了表征。MTBTM和VAc、MTBTM和St、ETBTM和VAc、ETBTM和St的共聚物均可溶于多种普通有机溶剂中。在常温下,MTBTM与VAc共聚物和ETBTM与VAc共聚物为透明的弹性体,MTBTM与St共聚物和ETBTM与St共聚物为白色脆性固体。     

Thermal dissociation behavior of copolymers bearing hemiacetal ester moieties and their reactions with epoxides

Copolymers from 1‐propoxyethyl methacrylate and various vinyl monomers such as n‐butyl methacrylate and styrene were synthesized, and the thermal dissociation reaction of the copolymers containing the hemiacetal ester structure was examined. The copolymers, having the ability of thermal dissociation, could control the thermal dissociation temperature because of the bulkiness and flexibility of the vinyl comonomers, the copolymer compositions, and so on. Furthermore, the possibility of control of the initiation in thermally latent addition with epoxides in the case of copolymers was also studied. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3966–3977, 2006     

Synthesis and polymerization of p-(p′-vinylbenzoyl)-peroxybenzoic acid tert-butylester: A monomer containing a photodissociable radical source

In a previous report we have shown that efficiently photodecomposable, but thermally stable, peresters can be made from a compound that contains both a triplet photosensitizer functionality and a perester group. This fundamental approach has been extended to make a novel vinyl monomer containing a triplet sensitizer and a perester group. Thus, the monomer p-vinylbenzoyl-p-tert-butyl perbenzoate (VBPE) has been synthesized and polymerized by normal procedures without loss of perester activity. The resulting polymer perester can be used as an efficient photolabile radical source by irradiating at the λ_max of the benzophenone carbonyl moiety. The homopolymer (PVBPE) and copolymers with other monomers, such as styrene, could be photocrosslinked with high efficiency. Copolymers of VBPE and styrene containing low percentages of VBPE have been used to initiate graft chains of poly(methyl methacrylate) by irradiating a solution of the copolymer in methyl methacrylate at 366 nm.     

Fluorocyclopropanes. IV. Copolymers of perfluorocyclopropene

Perfluorocyclopropene undergoes free-radical copolymerization with ethylene, isobutylene, cis- and trans-2-butene, vinyl acetate, methyl vinyl ether, vinyl chloride, styrene, acrylonitrile, tetrafluoroethylene, vinyl fluoride, and vinylidene fluoride. The copolymerization proceeds most readily with electron-rich olefins such as methyl vinyl ether (to yield a 1:1 copolymer), but conditions were found to give copolymers with electron-deficient olefins such as tetrafluoroethylene and vinylidene fluoride. Copolymers with methyl vinyl ether, tetrafluoroethylene, vinyl fluoride, and vinylidene fluoride were examined in detail. Evidence is presented that the perfluorocycloproply ring is incorporated intact into the copolymer and can be subsequently isomerized to a perfluoropropenyl unit by heating at 200–300°C.     

Copolymerization of studies. Copolymerization of methyl α-cyanocrotonate with styrene,acrylonitrile, and vinyl acetate

Copolymers of methyl α-cyanocrotonate with styrene, acrylonitrile, and vinyl acetate were prepared in bulk by free radical initiation. The copolymerization parameters were determined for each pair by several methods. The basic properties, that is, intrinsic viscosity, solubility, melting range, and glass transition temperature of the obtained copolymers, were determined.     

Thermal degradation of graft copolymers of PVC prepared by mastication with styrene and methyl methacrylate,and of further PVC mixtures and vinyl chloride copolymers

Graft copolymers prepared by mastication of PVC in the presence of styrene or of a styrene/ methyl methacrylate mixture, have been studied by thermogravimetry, estimation of hydrogen chloride, thermal volatilization analysis, and flash pyrolysis/g.l.c. The degradation behaviour of PVC/ polystyrene mixtures, vinyl chloride/styrene random copolymers, a random copolymer of methyl methacrylate and styrene, and PVC/poly-α-methylstyrene mixtures has also been studied. The graft copolymers resemble the PVC/methacrylate graft copolymers previously studied in showing retardation of the dehydrochlorination reaction, but contrast with them in yielding chain fragments but no monomer during HCl production. Some stabilization of the second component at higher temperatures is also found. PVC/polystyrene mixtures behave in the same way as the corresponding graft copolymers, but vinyl chloride/styrene copolymers show reduced stability towards both dehydrochlorination and monomer production compared with the homopolymers. PVC/poly-α-methylstyrene mixtures yield some monomer concurrently with HCl loss, and display marked retardation of the latter reaction. Stabilization of the second polymer at higher temperatures is again observed. Many of these results add further strong support to the view that chlorine atoms are involved as chain carriers in the thermal dehydrochlorination of PVC.     

对-氯甲基苯乙烯共聚物引发合成接枝共聚物

接枝共聚物含有性质差别很大的主链和支链,具有许多特殊的性质,因而一直是人们感兴趣的研究课题之一^[1～5].原子转移自由基聚合(ATRP)^[6,7]的问世,为接枝共聚物的合成提供了一条新的途径.本文用对-氯甲基苯乙烯和其它乙烯基单体自由基共聚.     

Vinyl polymerization. 410. Polymerizations of vinyl monomers initiated by poly(styrene-co-sodium acrylate) or poly(methyl methacrylate-co-sodium methacrylate). A verification of the concept of hard and soft hydrophobic areas and monomers

It was found that the copolymers of sodium acrylate (AA-Na) with styrene (St) and of sodium methacrylate (MAA-Na) with methyl methacrylate (MMA) could polymerize vinyl monomers in an aqueous phase without the usual initiator. Interestingly, there was a definite composition of the copolymer for the polymerization of a given monomer; for example, when poly(St-co-AA-Na) was used, St, MMA, vinyl acetate, ethyl acrylate, methyl acrylate, and acrylonitrile were polymerized by the copolymer having mole ratios of AA-Na:St of 0.61:0.29, 0.47:0.53, 0.38:0.62, 0.30:0.70, 0.24:0.76, and 1.00:0, respectively. The copolymers of various compositions can form hydrophobic areas (HAs) in the water phase. As has been repeatedly reported, the polymerization proceeds in the HAs, and the following new hypothesis was recently proposed that the hard (the less hydrophilic) HA prefers to incorporate the hard monomer and the soft (the less hydrophobic or the more hydrophilic) HA prefers to incorporate the soft monomer. The results mentioned above support this hypothesis.     

Formation of block copolymers from polyurethanes containing reactive disulfides

Block copolymers containing polyether segments and segments of a vinyl polymer have been synthesized. A low molecular weight polyether terminated with isocyanate groups was condensed with bis-(β-hydroxyethyl disulfide) to give polyurethanes containing reactive disulfide linkages. When this polymer was photolyzed in the presence of a vinyl monomer such as styrene, methyl methacrylate, or acrylonitrile, homolytic cleavage of the disulfide polymerized the monomer, giving block copolymers. The mechanical properties of the products were investigated by means of modulus–temperature measurements.     

Ionic-conductivity switching of vinyl malachite green leuconitrile copolymers based on photoinduced carrier generation

Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc.     

Macromolecular N-nitroso-acylamines as initiators for polyreactions. I. Synthesis of block copolymers from polycondensates and olefinic monomers,

The synthesis of block copolymers in three-step reactions from linear polycondensates (e.g., nylon 6. nylon 6,6, nylon 6,10 and polyurethane) and olefinic monomers (e.g., styrene, acrylic acid and acrylonitrile, methyl methacrylate, vinyl acetate, vinyl chloride, and isoprene) is reported. Macromolecular radicals are formed by the thermal decomposition of partly nitrosated peptide group containing polycondensates at elevated temperatures (60–200°C). These polyradicals initiate the copolymerization of the olefinic monomers. The conversion and reaction rates were generally high (up to 100% within a few hours). Most of the block copolymers prepared were soluble in organic solvents. Some, however, were insoluble or rubberlike. The reaction mechanism involved are analyzed. Applications are discussed.     

Block copolymers derived from azobiscyanopentanoic acid. X. Synthesis of silicone–vinyl block copolymers via polysiloxane(azobiscyanopentanamide)s

The synthesis of silicone–vinyl block copolymers has been studied by the use of poly(azo-containing siloxaneamide)s (abbreviated as PASAs), i.e., polysiloxane (azobiscyanopentanamide)s as macroazoinitiators. PASAs with number-average molecular weight of 12000–31000 and with siloxane chain lengths of 250–9800 were prepared by the condensation of azobiscyanopentanoyl chloride and α,ω-bis(3-aminopropyldimethyl)polysiloxanes in equimolar feeds. Several kinds of silicone–vinyl block copolymers were synthesized by radical polymerization of vinyl monomers such as methyl methacrylate, styrene, and vinyl acetate, in the presence of PASA in homogeneous media. The block copolymers with siloxane contents up to 30 mol % were then characterized on the basis of infrared absorption, proton NMR spectra, and gel permeation chromatography.     

Novel cyano-containing copolymers of vinyl esters for piezoelectric materials

The synthesis of a series of novel cyano-containing copolymers is described. Alternating copolymers of acrylonitrile with vinyl esters are obtained by increasing the electrophilic character of the nitrile monomers by complexation with zinc chloride. Copolymers of methyl and ethyl α-cyanoacrylates with vinyl esters are prepared using radical initiators in the presence of 7% acetic acid as inhibitor for anionic polymerization. The copolymers of methyl α-cyanoacrylate with the vinyl esters have T_g's above 140°C. Methyl vinylidene cyanide (MVCN) copolymerizes spontaneously with para-substituted styrenes to yield copolymers with high inherent viscosities and high T_g (160°C) and the copolymer of MVCN with vinyl acetate is also synthesized. The pyroelectric constants p for these polymers were measured and the values of p for the copolymers of vinyl acetate with methyl β,β-dicyanoacrylate, methyl α-cyanoacrylate, or MVCN were in the same range as the well-studied vinylidene cyanide/vinyl acetate copolymer. A higher concentration of dipoles generally results in higher T_g's and higher pyroelectric coefficients. © 1992 John Wiley & Sons, Inc.     

Free-Radical Copolymerizations of N-Phenyl Maleimide

Free radical-initiated copolymerization of N-phenyl maleimide (NPMI) with styrene (St), vinyl acetate (VAc) and methyl meth-acrylate (MMA) at 35°C in benzene solution initiated by AIBN was studied. The copolymerization of NPMI and St yields a “nearly equimolecular” alternating copolymer, irrespective of monomer feed. Reactivity ratios of NPMI with St, VAc, and MMA were determined by a curve-fitting method which has the advantage of delivering values not involving personal judgement. Q₁ and e₁ values of NPMI were also calculated. Tentative explanations have been proposed to Interpret the “nearly alternating” copolymerization between NPMI and St. In addition, thermal stabilities of copolymers were studied by using a programmed thermo-gravimetric analysis technique. Copolymers of St, VAc, and MMA show a considerable increase in thermal stability with increasing content of NPMI. The glass transition temperatures of copolymers of NPMI with MMA and St were measured by differential scanning calorimetry. In both series of copolymers the glass transition temperature increases markedly with increasing in NPMI content. In the case of NPMI-St copolymers, the relative thermal stability as well as glass transition temperature also corroborated the nearly alternating behavior observed.     

Sequence distribution of partially hydrolyzed poly(vinyl acetate)

Copolymers of vinyl acetate and vinyl alcohol were studied by differential thermal analysis. The melting points of the copolymers are not a simple function of the composition, but depend on the method of preparation of the copolymers. Partial saponification of poly(vinyl acetate) with sodium hydroxide leads to high melting, ordered copolymers, while reacetylation of poly(vinyl alcohol) leads to low melting, random copolymers. Catalytic alcoholysis of PVAc yields copolymers intermediate in melting point and order. The results are treated by assuming that equal melting points indicate similar sequence length distributions of crystallizable units.