HEMA—NVP—St三元共聚体系中单体的表观竞聚率

本文采用计算机数字积分和单纯形调优法根据Alfrey-Goldfinger共聚方程微分式,从HEMA-NVP—St三元共聚高转化率体系的转化率一组成数据,直接求算了各单体的表观竞聚率,用求得的表观竞聚率计算的转化率一组成曲线,与实验值符合很好。讨论了单体部分互溶对表观竞聚率的影响。发现在此三元共聚体系中,引入少量的均化剂,可以明显改善St与其它单体的互溶程度,使相应的表观竞聚率显著降低。     

Synthesis and polymerization of N-[1-(1-substituted-2-oxopropyl)]acrylamides and -methacrylamides. copolymerization of these monomers with styrene and substituent effects

The synthesis and polymerization of N-[1-(1-substituted-2-oxopropyl)]acrylamides and -methacrylamides are described. Seven new monomers were prepared by two kinds of synthetic procedure. The polymerization of these monomers was carried out. Monomer reactivity ratios in the polymerization of these monomers with styrene were determined and the Alfrey-Price Q and e values calculated. The effects of substituents on the reactivities in copolymerization were observed, and an interpretation of the results is given.     

Monomer reactivity ratios in graft copolymerization

This paper discusses monomer reactivity ratios in various radiation- and redox-initiated graft copolymerizations. The polymers studied were polyethylene, cellulose acetate, poly(vinyl chloride), polytetrafluoroethylene, poly(vinyl alcohol), and poly(methyl methacrylate); the comonomer mixtures were styrene–acrylonitrile, methyl acrylate–styrene, acrylonitrile–methyl acrylate, and vinyl acetate–acrylonitrile. The polymer–comonomer mixture systems were so chosen as to permit study of both homogeneous and heterogeneous systems. The homogeneous systems included systems of low and high viscosity. The heterogeneous systems included both polymers swollen by the comonomer mixture and polymers not swollen by the comonomer mixture. None of the homogeneous grafting systems studied showed deviations from the normal copolymerization behavior under a variety of experimental conditions. Monomer reactivity ratios in graft copolymerization were the same as the values in nongraft copolymerization. The heterogeneous systems in which the polymer was swollen by the comonomer mixture yielded grafted copolymer compositions which were the same as those in nongraft copolymerization. The heterogeneous grafting system polytetrafluoroethylene/styrene–acrylonitrile showed deviations from normal copolymerization behavior at low degrees of grafting when the reaction was only on the polymer surface. The behavior became normal at higher degrees of grafting when the system approaches that in which the polymer is swollen by the comonomers. In all reaction systems, it was found that the use of radiation to initiate the reaction does not in any way affect the copolymerization behavior of the two monomers in a comonomer pair.     

Copolymerization of acrylamide and styrene. II. Reactivity ratios with unperturbed acrylamide

It was reported earlier that the copolymerization of acrylamide and styrene is strongly affected by the copolymerization medium. The effect was attributed to a change in the polarity of the ethylenic bond in the acrylamide monomer due to hydrogen bonding and/or dipole—dipole interaction, depending on the medium. In view of those findings, it was suggested that absolute values for the reactivity ratios for the copolymerization of these two monomers might be obtained only when the acrylamide monomer is unperturbed. Copolymerizations of these monomers at a number of ratios, therefore, were done in benzene, which does not undergo hydrogen bonding and has no dipole moment, at high dilution, when amide—amide interactions between acrylamide molecules should be essentially eliminated. The values of r₁ and r₂(M₁ = acrylamide) were 9.14 ± 0.27 and 0.67 ± 0.08, respectively. There appears to be some indication in this system that high dilution adversely affects the reactivity of the acrylamide monomer while enhancing that of styrene. This aspect requires more study.     

Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. I. Propagation and initiation of the copolymerization of acrylonitrile with styrene copolymer

Copolymerization of acrylonitrile with styrene spontaneously occurred on addition of zinc chloride without addition of any other radical initiator. The composition of the copolymer approached that of strictly alternating copolymer as zinc chloride added to the copolymerization system increased. The significance of the apparent monomer reactivity ratios of this copolymerization system was studied from a kinetic point of view, and it was shown that the monomer sequence distribution is indicated by the apparent monomer reactivity ratios. Further, equations which represent the relation between the apparent monomer reactivity ratios and Q,e values at a given salt concentration were derived. These equations reasonably accounted for the decrease of the apparent monomer reactivity ratios of the copolymerization of acrylonitrile with styrene in the presence of zinc chloride and the behavior of the other acrylonitrile copolymerization systems in the presence of zinc chloride. The initiation step of the spontaneous radical copolymerization of acrylonitrile with styrene in the presence of zinc chloride was explained by a cross-initiation mechanism.     

Statistical copolymers of styrene and 2-vinylpyridine with trimethylsilyl methacrylate and trimethylsilyloxyethyl methacrylate

Statistical copolymers of styrene with trimethylsilyl methacrylate, STMS, and trimethylsilyloxyethyl methacrylate, STME, and of 2-vinylpyridine with trimethylsilyloxyethyl methacrylate, VTME were prepared by free radical copolymerization in benzene with 2,2′-azobisisobutyronitrile, AIBN. The reactivity ratios of the different monomers were estimated using the Finemann-Ross, the inverted Finemann-Ross, and the Kelen-Tüdos or the extended Kelen-Tüdos graphical methods. Structural parameters of the copolymers were obtained by calculating the diad sequence fractions, which were derived using the monomer reactivity ratios. The results were compared with those obtained from the copolymerization of styrene and 2-vinylpyridine with methacrylic acid and 2-hydroxyethyl methacrylate.     

Studies on propagating species in cationic polymerization of styrene derivatives by acetyl perchlorate or iodine. III. Effect of salt on cationic copolymerization of styrene derivatives with vinyl ethers by acetyl perchlorate

A common-ion salt, tetra-n-butylammonium perchlorate, was found to affect the monomer reactivity ratios in the cationic copolymerization by acetyl perchlorate of styrene with p-methylstyrene and of 2-chloroethyl vinyl ether with p-methylstyrene, but not those for the copolymerization of 2-chloroethyl vinyl ether with isobutyl vinyl ether. In the copolymerization of p-methylstyrene with styrene or with 2-chloroethyl vinyl ether, the addition of the common-ion salt in a polar solvent shifted the monomer reactivity ratios to those in a less polar solvent. The molecular weight distribution analysis of the copolymer suggested that the addition of the common-ion salt depresses the dissociation of propagating species. Therefore, it was concluded that a propagating species with a different degree of dissociation shows a different relative reactivity towards two monomers. The nature of propagating species was also discussed on the basis of the common-ion effect on the monomer reactivity ratios in various solvents.     

MEASUREMENTS OF MONOMER REACTIVITY RATIOS FOR COPOLYMERIZATION OF STYRENE AND METHYL METHACRYLATE IN CARBON DIOXIDE AT VAPOR-LIQUID EQUILIBRIUM STATE

The monomer reactivity ratios of free radical copolymerization of styrene and methyl methacrylate in carbon dioxide at vapor-liquid equilibrium state(vlCO_2)at 65℃and under 7.5-8.5 MPa were measured.The experimental results showed that,in comparison with the data in bulk copolymerization,the monomer reactivity ratio of St in vlCO_2 increased acompanied by a somewhat decrease in that of MMA.Further analysis of the sequence distributions of these copolymers by ~1H-NMR spectra indicated that there was a sig...     

N-vinylthiopyrrolidinone

The polymerization reactivity of N-vinylthipyrrolidinone is described. This monomer readily homopolymerizes and forms copolymers with a wide variety of vinyl monomers. Reactivity ratios in the copolymerization of N-vinylthiopyrrolidinone with styrene and methyl methacrylate are reported and the Alfrey-Price Q and e values calculated. These results indicate the high copolymerization reactivity of this monomer in comparison with the oxo-analog, N-vinylpyrrolidinone. Some of the results are in conflict with previously reported data.     

Microemulsion copolymerization of styrene and acrylonitrile with n‐butanol as the cosurfactant

The microemulsion copolymerization of styrene and acrylonitrile in an n‐butanol/cetyltrimethylammonium bromide/oil/water microemulsion system was studied. The solubilization sites of the two monomers were determined with an NMR technique. The results showed that the solubilization behaviors of the two monomers were quite different. Most of the styrene was solubilized in the palisade layer of the microemulsion, whereas the acrylonitrile had an equilibrium distribution in the aqueous phase and palisade layer of the microemulsion. The reactivity ratios of styrene and acrylonitrile in the microemulsion system were different from those in other media. The effect of the monomer feed composition on the copolymerization kinetics was investigated, and the mechanism of nucleation of the latex particles was examined. The experimental results showed that the copolymerization loci were changed from the microemulsion droplets to the aqueous phase when the concentration of acrylonitrile in the monomer feed reached approximately 80%; this could be further proved by the effect of the monomer feed composition on the copolymerization kinetics. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 203–216, 2005     

Estimation of Reactivity Ratios in the Copolymerization of Styrene and VeoVa‐10

The styrene and vinyl neodecanoate copolymerization system shows a strong tendency to form two separate homopolymers. In order to improve the feeding strategies and hence the copolymer uniformity, it is necessary to know the reactivity ratios between these monomers. The error‐in‐variables‐method (EVM) is the most recommended mathematical procedure for estimating these parameters. Experiments on free‐radical copolymerization in solution in sealed ampoules are carried out to provide data for the conversion (via gravimetry) and fractional monomer compositions (via Fourier transform mid‐infrared (mid‐FT‐IR) spectroscopy). These data allow estimation of the reactivity ratios. EVM appropriately takes into account the experimental errors in the data and allows determination of the reactivity ratio values by the Mayo–Lewis model (r₁ = 28.60 and r₂ = 1.23). The convergence and robustness of the method decrease considerably with a larger discrepancy between the reactivity values.     

二乙基二烯丙基氯化铵与丙烯酰胺、丙烯酸共聚竞聚率

二乙基二烯丙基氯化铵;丙烯酰胺;丙烯酸;共聚合;竞聚率     

Synthesis and characterization of copolyperoxides of indene with styrene, α‐methylstyrene,and α‐phenylstyrene

The oxidative copolymerization of indene with styrene, α‐methylstyrene, and α‐phenylstyrene is investigated. Copolyperoxides of different compositions have been synthesized by the free‐radical‐initiated oxidative copolymerization of indene with vinyl monomers. The compositions of the copolyperoxides obtained from the ¹H and ¹³C NMR spectra have been used to determine the reactivity ratios of the monomers. The reactivity ratios indicate that indene forms an ideal copolyperoxide with styrene and α‐methylstyrene and alternating copolyperoxides with α‐phenylstyrene. Thermal degradation studies via differential scanning calorimetry and electron‐impact mass spectroscopy support the alternating peroxide units in the copolyperoxide chain. The activation energy for thermal degradation suggests that the degradation is dependent on the dissociation of the peroxide (? O? O? ) bonds in the backbone of the copolyperoxide chain. Their flexibility has been examined in terms of the glass‐transition temperature. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2004–2017, 2002     

Synthesis and characterization of styrenic polymers with pendant pyrazole groups. II

The synthesis of styrenic monomers that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with maleic anhydride (MA) and N-(3-acetoxy propyl) maleimide is reported. The monomers were prepared from the Williamson reaction between 2-pyridine carbinol, hydroxy monopyrazole, hydroxy bipyrazole, and chloromethyl styrene. The homopolymerizations of such styrenic monomers were tried under different conditions, which led to low molecular weight polymers with a high polydispersity. However, alternating copolymers were obtained using maleic anhydride or N-(3-acetoxy propyl) maleimide as comonomers, as shown by ¹H-NMR, elemental analysis, and reactivity ratios r₁ and r₂. Furthermore, the hydrolysis of the acetate function of different copolymers was performed quantitatively. Unlike the acetoxy copolymers, such products do not have any glass transition temperature. Thermogravimetric investigations have shown that these copolymers exhibit good thermostability. © 1994 John Wiley & Sons, Inc.     

Radical Copolymerization of Acrylic Monomers. II Effect of Solvent on Radical Copolymerization of Methyl Methacrylate and Styrene

The influence of various solvents on the copolymerization behavior of methyl methacrylate with styrene has been investigated. In these systems there is a significant solvent effect on both r_S and r_M which may be attributed to changes in the dielectric constant of the solvents used. The calculated relative reactivity of the polystyryl radical towards the methyl methacrylate monomer increases with increasing solvent polarity, whereas the reactivity of poly(methyl methacrylate) radical towards styrene monomer decreases. The results obtained are discussed taking into account the behavior of both monomers in homopolymerization with the same experimental conditions as in copolymerization.     

Effect of monomer/nanoclay interaction on the kinetics of atom transfer radical homo- and copolymerization of styrene and methyl acrylate

Atom transfer radical homo- and copolymerization of styrene and methyl acrylate initiated with CCl₃-terminated poly(vinyl acetate) macroinitiator were performed at 90°C in the presence of nanoclay (Cloisite 30B). Controlled molecular weight characteristics of the reaction products were confirmed by GPC. It was shown that nanoclay slightly decreased the rate of styrene polymerization, while it significantly enhanced the rate of methyl acrylate polymerization and its copolymerization with styrene. The reactivity ratios of the monomers in the presence and in the absence of nanoclay were calculated (r _St = 1.002 ± 0.044, r _MA = 0.161 ± 0.018 by extended Kelen-Tudos method and r _St = 1.001 ± 0.038, r _MA = 0.163 ± 0.016 by Mao-Huglin method), confirming that the presence of nanoclay has no influence on monomer reactivity. The enhancement in the homopolymerization rate of methyl acrylate as well as its copolymerization rate with styrene was attributed to nanoclay effect on the dynamic equilibrium between active (macro)radicals and dormant species. Dipole moments of the monomers were successfully used to predict structure of the polymer/clay nanocomposites prepared via in situ polymerization.     

Synthesis,structure, and properties of bifunctional azobenzene monomers and polymers on their basis

A new preparative procedure for the synthesis of new bifunctional azo monomers with different ratios of methacryloyl and hydroxyl groups has been developed. The monomers thus prepared contain a nonlinear optical 4′-amino-4-nitroazobenzene group and can be involved in polymerization, polycondensation, and polymer-analogous transformation reactions to afford linear and network polymers. The free-radical copolymerization of 4′-[N-methyl-N-(3-methacryloyloxy-2-hydroxypropyl)]amino-4-nitroazobenzene with methyl methacrylate has been studied with the aim of preparing azobenzene [1+0] prepolymers with pendant chromophore groups, and the reactivity ratios and reactivity factors of the comonomers have been calculated. The hydroxyl-containing copolymers are characterized by rather high molecular mass, satisfactory heat resistance and thermal stability, and good film-forming behavior. These copolymers may be crosslinked with the use of diisocyanates and thus may form thin optically homogeneous red films.     

乙烯基聚硅氧烷共聚反应竞聚率的测定及其对复合粒子形态的影响

用Ｆｉｍｅｍａｎ－Ｒｏｓｓ法处理数据，测定了乙烯基聚硅氧烷（ＳＶ）与苯乙烯（ＳＴ）、甲基丙烯酸甲酯（ＭＭＡ）和甲基丙烯酸正丁酯（ｎ－ＢＭＡ）的共聚反应的竞聚率，结果为ｒＳＴ＝１．４５和ｒＳＶ＝１．０８，ｒＭＭＡ＝０．７８和ｒＳＶ＝２．０１，ｒｎ－ＢＭＡ＝０．４６和ｒＳＶ＝３．４９．以含ＳＶ的乳液作为种子进行烯类单体的乳液聚合，单体和ＳＶ共聚反应对复合粒子的形态有很大影响。     

Synthesis and characterization of thiophene‐substituted N‐phenyl maleimide polymers by photoinduced radical polymerization

Two types of novel functionalized N‐[4‐(4′‐hydroxyphenyloxycarbonyl)phenyl]maleimide and N‐(4‐{[2‐(3‐thienyl)acetyl]oxyphenyl}oxycarbonylphenyl)maleimide (MIThi) were synthesized starting from 4‐maleimido benzoic acid. Photoinduced radical homopolymerization of MIThi and its copolymerization with styrene were performed at room temperature to give linear polymers containing pendant thienyl moieties using ω,ω‐dimethoxy‐ω‐phenylacetophenone as an initiator. Copolymers' compositions and the equilibrium constant (K) for electron donor–acceptor complex formation suggest an alternating nature of the copolymerization. The monomer reactivity ratios and Alfrey–Price Q,e values were also determined. The thermal behavior of the new synthesized monomers and polymers was investigated by differential scanning calorimetry and thermogravimetric analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 995–1004, 2002     

Some aspects of copolymerization of dienes under the influence of π-allyl complexes of nickel

π-Allyl complexes of nickel induce stereospecific homopolymerization of cyclohexadiene-1,3 and 2,3-dimethylbutadiene with the formation of crystalline polymers. These polymers consist of 1,4-monomer units in cis-configuration for polycyclohexadiene and in trans-configuration for poly-2,3-dimethylbutadiene. Peculiarities of copolymerization of cyclohexadiene-1,3 with butadiene and isoprene and of 2,3-dimethylbutadiene with butadiene under the influence of various π-allyl complexes of nickel are studied. By i.r.- and NMR-spectroscopy and radiochemical methods, the composition of copolymers for the above pairs of monomers are determined and the reactivity ratios are found. Influence of the monomers on the microstructure of the chain in copolymerization is established; the mechanism of this phenomenon is discussed.