醋酸乙烯酯与1-(2-叔丁基过氧异丙基)-3-异丙烯基苯(D120)的共聚行为研究

共聚合;竞聚率;过氧化物;醋酸乙烯酯与1-(2-叔丁基过氧异丙基)-3-异丙烯基苯(D120)的共聚行为研究     

Swelling Ratios and Rates of Sulfonation of Solvent Modified Copolymers of Styrene Cross-Linked with Pure m-and Pure p-Divinylbenzene

Solvent-modified (toluene) copolymers have been prepared from styrene cross-linked with commercial divinylbenzene, m-divinylbenzene, and p-divinylbenzene at divinyl monomer contents of 16 mole % and 32 mole % at F_M = 0.50. The resultant copolymers have been characterized by swelling-ratio determinations and rates of sulfonation at 60 and 80°C. The solvent-modified 16 mole % cross-linked copolymers sulfonated at rates slightly greater than those characterizing the 8 mole % cross-linked copolymers prepared in the absence of diluent. The order of decreasing sulfonation rates for both the conventional 8 mole % cross-linked systems and for the solvent-modified 16 mole % cross-linked copolymers is commercial divinylbenzene/styrene, p-divinylbenzene/styrene, m-divinylbenzene styrene. The 32 mole % cross-linked systems exhibit a different order of decreasing sulfonation rates: commercial divinylbenzene/styrene, m-divinylbenzene/styrene, p-divinylbenzene/styrene. The swelling ratios of the 32 mole % solvent-modified copolymers were comparable to those of the conventional 8 mole % cross-linked systems.     

Copolymerization of vinyl cyclohexane and α-methyl vinyl cyclohexane with acrylonitrile

Copolymerization of vinyl cyclohexane and α-methyl vinyl cyclohexane with acrylonitrile in the presence of a complexing agent AlEtCl₂ results in the formation of alternate copolymers. In the copolymerization of vinyl cyclohexane with acrylonitrile the copolymer composition depends on the ratio of acrylonitrile to AlEtCl₂. If this ratio is unity, alternating copolymers of the composition 1:1 are formed; with a ratio greater than unity statistical copolymers that contain more than 50% acrylonitrile units are produced. The ¹H-NMR spectroscopy measurements indicate that the interaction between the comonomers and the complexing agent leads to the formation of ternary donor–acceptor complexes of equimolar composition. The equilibrium constants of these complexes at ?60°C have been determined. The effects of temperature, nature of solvent and dilution on the yield, and composition of the copolymers of vinyl cyclohexane with acrylonitrile formed have been studied. By lowering the temperature the yield of copolymers increases but their composition remains equimolar. An increase in the polarity of the medium results in an increase in copolymer yield, whereas the yield decreases if the reaction is conducted in a donor-solvent medium. Dilution of the reaction mixture disrupts the alternation of units in the macrochain of copolymers. The kinetic pecularities of copolymerization have been investigated. The linear dependence of the copolymerization rate on the product of comonomer concentration is observed. The rate of copolymerization is proportional to the square root of the incident light intensity. Various additions of radical type and irradiation accelerate the process of copolymerization. The mechanism of alternating copolymerization of vinyl cyclohexane monomers with acrylonitrile in the presence of AlEtCl₂ is discussed in terms of homopolymerization of the comonomer complex.     

Anionic copolymerization of 2,3,4,5,6-pentafluorostyrene and divinylbenzene

Anionic copolymerizations of 2,3,4,5,6-pentafluorostyrene (PFS) with 1,3-divinylbenzene (m-DVB) and 1,4-divinylbenzene (p-DVB) were performed by using lithium diisopropylamide as an initiator in order to synthesize the fluorine-containing linear polymer with pendant vinyl groups. The products were soluble copolymers possessing both PFS and DVB monomeric units, and the DVB monomeric unit in copolymer had pendant vinyl group. This copolymerization reaction took a much longer time than that of styrene with DVB. The copolymerization parameter of this system was examined from copolymer composition curves. In this system, m-DVB was found to be more reactive than p-DVB. The reactivity of copolymerization was largely influenced by the reactivity of active species. © 1993 John Wiley & Sons, Inc.     

Controlled Composition in Emulsion Copolymerization Application to Butadiene-Acrylonitrile Copolymers

Abstract

The use of gas chromatographic analysis of the actual monomer mixture at fixed time intervals to monitor the composition of copolymers in emulsion copolymerization has been described previously. The design has been now improved by the insertion of a dilution cell to avoid flocculation problems in the loop carrying the reaction medium from the reactor to the injection kit of the chromatograph. Then the copolymerization can be monitored up to completion. This system has been applied to the copolymerization of butadiene and acrylonitrile, and constant composition runs have been compared to the batch. Two main differences are observed. (1) Constant composition copolymers show a unique glass transition interval of limited width instead of two or at least one broad temperature interval for the copolymer produced in batch. (2) In the monitored copolymerizations, the production of insoluble gels is delayed and sometimes totally avoided. The production of the gels is related to the formation of 1,2-butadiene units which appear to be preferentially present in long sequences of butadiene units. The cross-linking process involves the consumption of the pendent vinyl groups by copolymerization with the monomers.     

Copolymerization of styrene with vinyltriethoxysilane and vinyltriacetoxysilane

Styrene was copolymerized in bulk with vinyltriethoxysilane at 80°C and vinyltriacetoxysilane at 60, 80, and 100°C with the use of benzoyl peroxide as an initiator at low conversions. Copolymer composition was determined from the silicon content and reactivity ratios were calculated by the conventional scheme of copolymerization. The low r₁ value (styrene) in the styrene-vinyltriacetoxysilane system (St–VTAS) as compared to styrene-vinyltriethoxysilane (St–VTES) copolymerization may be attributed to higher reactivity of VTAS towards the polystyryl radical. Further, in the St–VTAS system, r₁ tends to decrease with increasing polymerization temperature. The influence of silicon comonomer on properties of the copolymers (intrinsic viscosity, solubility, dielectric and thermal behavior) was studied.     

Copolymerization of vinyl chloride with 1-vinyl-4,5,6,7-tetrahydroindole and 2-methyl-5-vinylpyridine

The radical copolymerization of vinyl chloride with 2-methyl-5-vinylpyridine and 1-vinyl-4,5,6,7-tetrahydroindole is accompanied by dehydrochlorination. In the vinyl chloride-2-methyl-5-vinylpyridine system, the evolved hydrogen chloride interacts with a pyridine hydrogen atom to give charged units of a heterocycle. In the vinyl chloride-1-vinyl-4,5,6,7-tetrahydroindole system, the hydrogen chloride being formed initiates the cationic dimerization of a nitrogen-containing monomer. The synthesized copolymers based on vinyl chloride surpass the commercial poly(vinyl chloride) in terms of thermal stability and solubility in organic solvents.     

Synthesis and characterization of maleimide polymers with pendant pyrazole groups. IV. Copolymerization of pyrazole-modified maleimides with vinyl ethers

The synthesis of maleimides that have pyrazolic or bipyrazolic pendant groups is described. Their homopolymerization and their copolymerization with 2-chloroethyl vinyl ether (CEVE) is reported. The homopolymerizations of such maleimides were performed under various conditions and led to low molecular-weight polymers. However, alternating copolymers were obtained from CEVE as comonomers whatever the monomers feed compositions. A similar behavior was also observed for maleimides that do not exhibit any spacer, whereas for bulky vinyl ethers, random copolymers were produced. A comparison of the thermal behavior between these copolymers (glass transition temperatures, T_g, and decomposition temperatures) and other copolymers having different spacers between the nitrogenated cycles and the chain are related. Thus, an important decrease of T_g, was observed when C₃H₆CO₂CH₂ groups were used as the spacer instead of methylene groups. Moreover, the thermal weakness of these copolymers may come from the substituents of the vinyl ether and is discussed. © 1994 John Wiley & Sons, Inc.     

Graft Copolymerization of Pyrrolidone onto Copolymers of N-Acryloyl Pyrrolidone and Vinyl Monomers

The copolymerizations of N-acryloyl pyrrolidone (NAP) with vinyl monomers methyl methacrylate (MMA), acrylonitrile (AN) and acrylamide (AA) were carried out in dimethylformamide at 65°C using 2,2′-azobisisobutyronitrile(AIBN) as an initiator. The resulting copolymers were used as a polymeric initiator of the anionic graft copolymerization of 2-pyrrolidone. The percent grafting of 2-pyrrolidone onto vinyl copolymer backbone chain involving N-acyllactam groups was found best with copoly(NAP-co-MMA) when the KOH concentration was 0.03 M. The presence of crown ether increased the viscosity of graft copolymers and accelerated the initial rate of anionic graft copolymerization.     

Copolymerization of acrylic acid amides with alkenyl halides

The binary radical copolymerization of acrylic acid amides (acrylamide and N-cyclohexen-1-ylacrylamide) with alkenyl halides (vinyl chloride, vinyl bromide, and allyl chloride) has been studied. The constants of relative activity of the monomers used are calculated. For the systems under investigation, the occurrence of dehydrochlorination of a polymer chain and protonation of a carbonyl group occur is confirmed. Allyl chloride shows the most pronounced tendency toward dehydrochlorination, while in the case of vinyl chloride, this tendency is the least distinct. The polymer-analogous transformations result in copolymers containing polyene fragments and units of ammonium or oxonium amide salts.     

醋酸乙烯—二乙烯基苯共聚反应动力学

根据文献查得的Ｑ，ｅ值，计算了醋酸乙烯－二乙烯基二元共聚的竞聚率，预测其共聚的可能性。以甲苯为汽油为致孔剂，采用悬浮聚合方法合成该二元大孔共聚物。红外光谱分析跟踪共聚反应过程中乙酰氧基和苯环相对比例的变化，并测定共聚反应过程中比表面积，孔率和平均孔径的变化。     

Copolymerization of Diethyl Vinyl Phosphate with Vinyl Acetate and Acrylonitrile

Free radical-initiated copolymerization of diethyl vinyl phosphate (DEVPA) with vinyl acetate (VAc) and acrylonitrile (AN) was studied. The monomer reactivity ratios for the monomer pairs, determined at 60°C using benzoyl peroxide as an initiator, are: r₁(VAc) = 0.95, r₂(DEVPA) = 0.93; r₁(AN) = 6.6, r₂(DEVPA) = 0.049. The values of the Alfrey-Price constants, Q and e, for DEVPA were calculated to be 0.025 and 0.13, respectively, from the VAc system, and 0.026 and 0.14, respectively, from the AN/DEVPA pair. These results indicate that the general reactivity of DEVPA is almost the same as that of VAc and that the diethylphosphate group is a stronger electron-attracting group than the acetoxy group. The intrinsic viscosity and number-average molecular weight of copolymers decreased as their content of DEVPA units increased, indicating a high degree of chain transfer caused by DEVPA.     

Copolymerization of vinyl acetate and unsaturated acids in the presence of germanium tetrachloride in methanol

The influence of catalytic amounts of germanium tetrachloride on the copolymerization of vinyl acetate with acrylic acid and methacrylic acid in methanol is examined. It is shown that germanium tetrachloride exerts different effects on the formation rate, molecular-mass characteristics, and composition of copolymers formed in these systems. For example, at a germanium tetrachloride-to-acrylic acid ratio of 0.02 (mol/mol), an alternating copolymer is formed, whereas in the case of methacrylic acid, a copolymer considerably enriched with methacrylic acid units is produced at the same ratio. The results are explained by different copolymerization mechanisms for both systems.     

Copolymerization reactivity of poly(methyl methacrylate) macromer

Poly(methyl mehtacrylate)(PMMA) macromers with several vinyl groups at both chain ends were synthesized by the mechanical scission reaction of the main chain in the presence of p-divinylbenzene(p-DVB). The radical copolymerization of this macromer with styrene(St) or MMA was carried out in benzene at 60°C and the reactivity ratio of both monomers (r₂) was calculated from a kinetic scheme of copolymerization. As a result, the effect of molecular weight and concentration of macromers was not observed in both copolymerization systems. The value of r₂, however, decreased as the number of end vinyl groups in a macromer (N) increased. These results are discussed in some detail as we describe the construction of the kinetic model of copolymerization.     

~(13)C-NMR研究丁二烯-异戊二烯共聚合的竞聚率和共聚物的序列分布

用~(13)C-NMR方法研完了不同配料比的丁二烯-异戊二烯本体共聚和溶液共聚物的结构,定量计算出了共聚物二元组的浓度和数均序列长度,采用T(?)DO″S法计算出了本体共聚和溶液共聚的竞聚率,并证明各种共聚产物的序列分布都服从一级Markov统计模型。     

Copolymerization of vinyl acetate with ethyl α-cyanocinnamate

Trisubstituted ethylene, ethyl α-cyanocinnamate, is readily copolymerized with vinyl acetate by a conventional radical initiator. Terminal, penultimate, and “complex” copolymerization models were applied by using the data of composition of the copolymers obtained in bulk and by copolymerization in benzene, ethyl acetate, and chloroform. The model based on the participation of the monomer complexes describes satisfactorily the deviation from the terminal copolymerization model. The proton NMR analyses of the monomer mixtures indicate that the interaction between the monomers leads to the formation of weak monomer complexes. Kinetic studies of the initial rate dependence on the total monomer concentration and monomer feed composition enabled us to evaluate the degree of participation of the free uncomplexed monomers and the monomer complex in the propagation reactions. The contribution of the complexed monomers in the propagation stages increases with the increase in total monomer concentration. The initial rate of the copolymerization is proportional to the square root of the initiator concentration, thus confirming the bimolecular termination of the macrochains. The rate constants of the addition reactions of the complex and free monomers were evaluated from the kinetic studies. The quantitative kinetic treatment provided information regarding the relative weight of the termination reaction and indicated that the termination in the system occurs predominantly by the cross-termination reaction between two growing polymer radicals with different kinds of monomer units at the ends. Additional information on the termination in this system was obtained from viscosity measurements.     

Cationic copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane

Copolymerization of 2-vinyl-1,3-dioxane with styrene and 1,3-dioxolane was carried out in methylene chloride at 0°C with triethyloxonium tetrafluoroborate as an initiator. Random copolymers were obtained from both of these monomer pairs, but attempted copolymerization of 2-vinyl-1,3-dioxane with 3,3-bis(chloromethyl)oxetane under similar conditions resulted in the homopolymer of the latter monomer. There were three structural units of 2-vinyl-1,3-dioxane in these copolymers as in its homopolymer: the “ester” unit, which was formed by vinyl addition with hydride shift followed by ring-opening rearrangement, the “vinyl” unit produced by ring-opening reaction, and the unit with a pendant 1,3-dioxane ring formed by simple vinyl addition. The fractions of the ester and vinyl units to the total 2-vinyl-1,3-dioxane units in the copolymer of 2-vinyl-1,3-dioxane with styrene decreased with decreasing 2-vinyl-1,3-dioxane content. On the contrary, the fraction of the vinyl unit in the copolymer of 2-vinyl-1,3-dioxane with 1,3-dioxolane increased slightly with decreasing 2-vinyl-1,3-dioxane content, while that of the ester unit decreased. The reactivities of the propagating species are discussed on the basis of these results.     

Radiometric Studies on Copolymerization of Multimethacrylate with Styrene

Abstract

Soluble copolymers containing ladder-type blocks are obtained as a result of free-radical copolymerization of a multifunctional monomer (multimethacrylate) with styrene in dilute solutions of DMF. The effects of some conditions of copolymerization on the number of end groups in a macromolecule, number of branching points, molar fraction of methacrylate units which reacted along the template chain, unsaturated residues, copolymer composition, and molecular weight were determined. The results obtained show that more than 80% of methacrylate units reacted along the template chain while the remaining units formed branches or did not participate in the process.     

异丁烯与对氯甲基苯乙烯正离子共聚合研究

以四氯化钛(TiCl4)、二氯乙基铝(AlEtCl2)、倍半铝(AlEt1.5Cl1.5)、三氯化铝(AlCl3)等路易斯酸为共引发剂,水或枯基醇(CumOH)为引发剂,在-80℃下的正己烷/二氯甲烷(V/V=6/4)的混合溶剂内,研究了异丁烯(IB)与对氯甲基苯乙烯(p-CMS)的正离子共聚合.利用示差凝胶渗透色谱仪(GPCRI)以及核磁氢谱(1H-NMR)对共聚物的表观分子量及分子量分布、共聚组成等进行分析,采用KelenTüd?s与Yezreielv-Brokhina-Roskin法计算了单体竞聚率,初步探讨了p-CMS与IB正离子共聚合的反应机理.结果表明,AlEtCl2、AlEt1.5Cl1.5、AlCl3均可催化大分子间的烷基化反应,产生凝胶;TiCl4作为共引发剂,可以得到无凝胶单峰分布共聚物;邻位氯甲基苯乙烯(o-CMS)不能参与共聚,p-CMS的共聚活性较低,IB与p-CMS的单体竞聚率为rIB=4.67,rp-CMS=0.70;随反应时间延长,共聚物中p-CMS的含量及共聚物分子量均逐渐增加;p-CMS单体自身几乎不参与引发,共聚到大分子链后,苄基氯缓慢参与引发,形成支化.提高共聚合温度至-60和-40℃,聚合速率降低,p-CMS的引发活性未发生明显变化.     

Copolymerization of ethylene with a vinyl ether bearing a fluorinated group

The copolymerization of ethylene (E) with 1H,1H,2H,2H-perfluorodecyl vinyl ether (FAVE8) by oxidative addition of salicylaldimine ligand to bis(1,5-cyclooctadiene)nickel(0)/methylaluminoxane (MAO) at room temperature and at different ethylene pressures is reported. The homopolymerization of ethylene is known to be highly active with this catalyst in contrast to the fluorinated vinyl ether which does not homopolymerize. The copolymerization of E with FAVE8 led to linear poly(E-co-FAVE8) statistic copolymers that were characterized by means of various techniques. The obtained copolymers, analyzed by FT-IR and solid state NMR spectroscopy, showed a small incorporation of the fluorinated vinyl ether. Three copolymerization reactions were investigated with different ethylene pressures (5, 10 and 50 bar) and the copolymer compositions indicated that the content of FAVE8 units depends on the ethylene pressure. The lower this pressure, the higher the content of such a fluorinated comonomer and for a 50 bar-pressure, no FAVE8 was incorporated. Thermogravimetric and differential scanning calorimetry analyses of these resulting copolymers exhibited high thermal stability, the thermal degradation starting from ca. 300 °C whereas high melting point (T_m = 129 °C) were achieved with these copolymers. Original films processed from these poly(E-co-FAVE8) copolymers illustrated hydrophobic and oleophilic characters as evidenced by water and diiodomethane contact angles of 104° and 49°, respectively.