碳酸乙烯酯溶剂中丙烯腈的聚合行为

以碳酸乙烯酯为溶剂,偶氮二异丁腈（AIBN）为引发剂,采用溶液自由基聚合的方法对丙烯腈(AN)均聚合、丙烯腈/衣康酸(AN/IA)二元共聚及丙烯腈/衣康酸/丙烯酸甲酯(AN/IA/MA)三元共聚合进行了研究。 考察了反应温度对丙烯腈均聚合,以及聚合单体浓度对丙烯腈共聚合的影响,在60 ℃合成了相对分子质量高于4.5×105、单体转化率高于85%的丙烯腈均聚物及共聚物。 采用正十二烷基硫醇（DDT）和甲酰基哌啶（FP）作为链转移剂,对AN均聚物、AN/IA及AN/IA/MA共聚物的相对分子质量进行调控,考察了链转移剂浓度对聚合物相对分子质量和单体转化率的影响。 结果表明,w(DDT)为0.25%时（以单体质量计）,聚合物相对分子质量可有效调节到1×105,而单体转化率保持在80%以上。     

N-甲基丙烯酰-N′-甲基哌嗪在嵌段聚醚氨酯膜上的Co~(60)-γ辐射接枝的研究

<正> 用亲水性单体对嵌段聚醚氨酯(SPEU)膜接枝共聚以改善其抗凝血性能,在医用材料的研究中已引起普遍重视,但由于一般化学方法接枝引发系统中带入的小分子常常对产品的医用性质造成不利的影响。我们曾报道通过Co~(60)-γ射线预辐照法用亲水性单体对以PTMG;MDI与不同的二胺类扩链剂制备的SPEU膜接枝共聚。本文在此基础上选用了两种单体AMP和MAMP。     

一种低分子量带有羧基的聚丙烯酸酯丙烯酸树脂的制备和性质

制备了一种紫外光固化预聚物——带有羧基的低分子量聚丙烯酸酯丙烯酸树脂(Polyacrylate acrylic resin, PAAR).其主链由丙烯酸烷基酯和丙烯酸进行共聚而得,当采用丙烯酸甲酯、丙烯酸乙酯和丙烯酸(摩尔比1:1:1)作为共聚单体,引发剂AIBN为1.5%,链转移剂十二硫醇为2.5%时,聚合得到的聚丙烯酸酯(Polyacrylate, PA)分子量在1100-1400之间,多分散性小于2,反应速率快,转化率高;由这种PA和甲基丙烯酸缩水甘油酯(GMA)进行酯化反应,制备得到最终产物聚丙烯酸酯丙烯酸树脂,酯化率可以达到80%以上,其光固化膜具有较好的涂膜硬度和柔韧性,光泽度饱满.     

两种双亲性聚合物自组装胶束复合水溶液的乳化性能

以苯乙烯(St)、含香豆素光敏单体(VM)、丙烯酸(AA)为单体,偶氮二异丁腈(AIBN)为引发剂引发自由基共聚,合成了双亲性光敏无规共聚物P(St-co-VM-co-AA)(简称PSVA);又以St及甲基丙烯酸二甲胺乙酯(DMAEMA)为单体,AIBN为引发剂引发自由基共聚,制得二元双亲性无规共聚物P(St-co-D...     

反丁烯二酸酯的自由基共聚反应

<正> 对反丁烯二酸酯(DRPs)类单休的均实反应研究已有许多报道。研究结果表明,所有的正烷基酯基DRFs单体,如反丁烯二酸二王丙酯等,均表现出很低的聚合反应活性,因而得不到高分子量的均聚物;而某些非正烷基酯的DRFs单体,如反丁烯二酸二异丙酯则显示出很高的聚合反应活性并可形成高分子量的聚合物。对反丁烯二酸酯同其他乙烯类单体(如苯乙烯等)的共聚研究曾有一些报道,但对DRFs单体之间的共聚     

甲基丙烯酸羟烷基酯与丙烯腈或丙烯酰胺共聚合的研究

测定了亲水性甲基丙烯酸羟烷基酯如HEMA、MHPMA分别与AN或AAM,在60℃不同溶剂中自由基聚合反应的竞聚率。AN(M_1)-HEMA(M_2)共单体,在DMSO或DMF溶剂以AIBN或KPS-IPA引发剂条件下共聚,用Kelen-Tüds法计算的竞聚率变化不大,r_1=0.22-0.25、r_2=0.97-1.05,说明在此均相溶液共聚中,所用的溶剂及引发剂对竞聚率的影响较小,这两种单体能很好共聚。但AAM-MHPMA或AAM-HEMA共单体时,r_1与r_2值相差很大,如前者r_1=0.0433、r_2=3.98,后者r_1=0.0535、r_2=1.89,说明不易共聚,共聚物中主要是MHPMA或HEMA组分。     

蒸馏沉淀聚合法制备窄分散聚二乙烯基苯-co-丙烯腈功能聚合物微球

采用蒸馏沉淀聚合法,利用过氧化苯甲酰(BPO)为引发剂,在不加任何稳定剂和不搅拌的情况下,丙烯腈(AN)和二乙烯基苯(DVB)为共聚单体制备了不同交联度的微米和亚微米窄分散聚合物微球,考查了共聚单体对球体的影响,并用扫描电镜(SEM)和红外光谱对微球进行了表征.     

一类三元共聚反应的拟二元化处理方法和简单稳态假定下的三元共聚的可拟二元化特性

对一类两种主单体比例保持恒定,微量或少量第三单体参与的改性三元共聚体系,采用了将两种主单体视为一种单体,微(少)量第三单体与此"主单体"进行拟二元共聚的处理方式,分别用动力学概念推导法和从三元共聚简易组成式直接导出法,推得拟二元共聚等效竞聚率计算式,两种方法所得结果一致.对文献报道的一些三元共聚实例进行了计算,证实了本...     

衣康酸对聚丙烯腈原丝结构和性能的影响

控制单体配比 ,采用丙烯腈 (AN)与衣康酸 (IA)自由基溶液共聚 ,以偶氮二异丁腈为引发剂在溶剂二甲基亚砜中合成了聚丙烯腈原丝纺丝溶液 ,并纺制了碳纤维前驱体聚丙烯腈原丝 .通过元素分析、IR、DSC、13 C NMR等手段 ,讨论了共聚单体IA对共聚反应及聚丙烯腈原丝结构和性能的影响 .共聚反应时 ,共聚单体IA的加入量控制在AN/IA =98/2 (W/W )较合适 .利用IR谱 ,可定量分析IA在共聚中的摩尔分数 .经13 C NMR分析 ,随着共聚单体IR在共聚物中的摩尔分数的增加 ,共聚物的全同规整度增加 ,达到一定值后又呈下降趋势 .共聚单体IA能在较低温度时引发聚丙烯腈原丝的氧化、环化放热反应 ,且能减缓放热效应 .     

无皂高分子纳米胶乳粒子的制备与稳定

在微波辐照下,以过硫酸钾(KPS)为引发剂,丙酮水溶液(质量比1∶ 1)为分散介质,进行了苯乙烯(ST)和其它共聚单体:甲基丙烯酸甲酯(MMA)、甲基丙烯酸丁酯(BMA)、丙烯酸乙酯(EA)及顺丁烯二酸酐(BDA)的无皂乳液聚合,得到了稳定的纳米胶乳粒子.讨论了共聚单体的种类和浓度对粒子水化半径的影响.增加配方中亲水性单体含量,使引发反应中引发剂的消耗量增加,粒子表面电荷密度增大,同时亲水性增加,油水界面张力减小,粒子变得稳定,有利于小粒子的生成.粒子的大小随亲水性单体的含量呈曲线关系,曲线上有最低点.     

马来酸酐与乙酸乙烯酯交替共聚合反应的研究

本文研究了马来酸酐（MAn）在过氧化苯甲酰（BP）引发作用下与醋酸乙烯酯（VAc）的交替共聚反应。红外光谱证明了交替共聚物的结构，分析结果表明共聚物是由反应单体技1：1摩尔比例组成。当c（BPO）＝6．8×10~（－3）moi／L，c（VAc）＝3．4×10~（－3）mol／L，p（MAn）＝32．7g／L，63～65℃反应18小时，转化率可达92％以上。     

马来酸酐和苯乙烯的可逆加成-断链链转移聚合及新型嵌段共聚物的合成

马来酸酐和苯乙烯是被广为研究的一对电荷转移复合物 (Ｃｈａｒｇｅｔｒａｎｓｆｅｒｃｏｍｐｌｅｘ,简称ＣＴＣ) ,而且能通过通常的自由基聚合发生交替共聚[1] .所得的聚合物由于酸酐基团的存在 ,很易进行大分子改性得到具有某些特殊功能的高分子 .不过 ,所得共聚物的分子量难以控制且分子量分布也较宽 .近年来发展起来的“活性” 可控自由基聚合越来越为人们所关注 ,因为采用这种方法不仅可对聚合物的分子量进行设计 ,同时分子量分布也较窄 ,也不需要活性离子型聚合那样严格的聚合条件 .关于烯类单体的活性自由基聚合迄今主要有氮氧自由基…     

Photocopolymerization of methacryloyl-L-valine methyl ester with maleic anhydride

Methacryloyl-L -valine methyl ester (MAVM) and maleic anhydride (MAn) were photopolymerized without initiator in dioxane at 35°C. Copolymer having a 1:1 molar ratio of the monomers was obtained regardless of both molar ratio of monomers in the feed and polymerization time. The circular dichroism (CD) spectrum of the copolymer before and after hydrolysis showed the induction of asymmetric centers into the polymer main chain. Spectroscopic and kinetic studies suggested the alternating and stereoregular copolymerization of MAVM and MAn, in which a charge transfer complex with a 1:1 molar ratio of monomers participated.     

Stabilizer‐free dispersion copolymerization of maleic anhydride and vinyl acetate. I. Effects of principal factors on microspheres

A novel dispersion copolymerization of maleic anhydride (MAn) and vinyl acetate (VAc) without adding stabilizer is developed, which gives uniform copolymer microspheres with tunable sizes. Some principal factors affecting the microspheres, such as reaction time, monomer concentration and feed ratio, reaction media, and cosolvent, were investigated. It was found that the stabilizer‐free dispersion copolymerization of MAn and VAc is a rapid process, and the particle size grows in accordance with the evolution of polymerization. The chemical composition of the copolymer microspheres was characterized by FT‐IR and ¹³C NMR spectroscopies. Over a wide range of monomer concentrations, the microspheres can always be formed and stably dispersed, with uniform sizes ranging from 180 nm to 740 nm. The yield of copolymer microspheres reaches a maximum at 1:1 feed ratio of MAn to VAc, owing to the alternating copolymerization between the binary monomers by a known charge‐transfer‐complex mechanism. However, the diameter of microspheres drastically increases when MAn content is enhanced. Only some specific alkyl ester solvents, such as n‐butyl acetate, isobutyl acetate, n‐amyl acetate, are desirably fit for this unique stabilizer‐free dispersion polymerization. Furthermore, we found that when some acetone is added as a cosolvent, the copolymer microspheres can still be formed, with much larger diameters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3760–3770, 2005     

稀土配位催化马来酸酐-苯乙烯-N-苯基马来酰亚胺三元共聚合

采用稀土配位催化剂研究了马来酸酐、苯乙烯和N 苯基马来酰亚胺的三元共聚合反应 .考察了Al La物质的量的比、不同稀土元素、催化剂浓度、聚合反应时间、单体配比等因素对共聚合反应的影响 .利用核磁、红外、热分析等方法对共聚物进行了初步的表征     

Contribution to the mechanism of copolymerization of phenylvinyl alkyl ethers and thioethers with maleic anhydride

The equilibrium constants of the charge-transfer complex monomers of phenylvinyl alkyl ethers (I) and thioethers (II) with maleic anhydride (MAn) were determined by the transformed Benessi—Hildebrand NMR method, and it was found that the bulkiness of alkyl groups had no significant influence on the equilibrium constant. The rate of copolymerization, however, was largely dependent on the bulkiness of the alkyl groups in the phenylvinyl alkyl ether series. The rate of copolymerization of I (R = Et; sec-Bu) and II (R = Et; sec-Bu) with MAn was proportional to the square root of AIBN concentration, and intrinsic viscosity of poly-I (R = Et)-co-MAn was proportional to the reciprocal square root of AIBN concentration. Spontaneous copolymerization did not occur, but I (R = Et) copolymerizes with MAn in the presence of oxygen; II did not copolymerize with MAn in the presence of oxygen; nor in the presence of peroxide initiators. In the copolymerization of I (R = Et) and MAn, it was found that molecular weight increases with conversion. By applying the generalized model described by Shirota and co-workers, the reactivity ratios k_1c/k₁₂ and k_2c/₂₁ for copolymerization of I (R = Et) and II (R = Et) with MAn were calculated from the change of copolymerization rate with monomer feed at constant total monomer concentration.     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.     

Stabilizer-free precipitation copolymerization of renewable bio-based α-methylene-γ-butyrolactone and styrene

Stabilizer-free precipitation copolymerization of α-methylene-γ-butyrolactone (MBL) and styrene (St) was carried out in isoamyl acetate with BPO as initiator at 80°C. The influence of monomer feed ratio, initiator concentration and reaction time on the size and morphology of the obtained polymer particle was investigated in details. It was found that the monomer feed ratio play an important role on the particle formation process. When the monomer feed ratio of MBL to St was 1:2, narrow size distributed spherical polymer particles were formed with number average diameters in the range of 785–2620 nm. The formation process of polymer particle was studied to get a deep insight into the polymerization process of this reaction system. It was found that the formation mechanism of the poly(MBL-co-St) particles was similar to that of conventional precipitation polymerization. After a short nucleation stage (10 min), the amount of polymer particles remained constant and the particle growth mainly came from the capturing of newly formed polymer chains. The chemical composition and thermal property of the poly(MBL-co-St) were fully characterized by FTIR, ¹H-NMR spectra, and DSC.     

FREE-RADICAL-INITIATED COPOLYMERIZATION OF 2-CHLOROSTYRENE, 4-CHLOROSTYRENE,AND 2,6-DICHLOROSTYRENE WITH MALEIC ANHYDRIDE

The title copolymers have been prepared by the free-radical-initiated copolymerization of 2-chlorostyrene (2-ClSt), 4-chlorostyrene (4-ClSt) and 2,6-dichlorostyrene (2,6-DClSt) with maleic anhydride (MAn) in toluene at 65°C. Copolymers of chlorinated styrenes with MAn prepared under different monomer-to-monomer ratios in the feed have alternating composition. In all cases, the mixture of comonomers forms charge-transfer complex monomers (CTC). The initial rate of copolymerization increases with the increase of electron donors in the comonomer feed, and the highest rates were at the equimolar ratios of comonomers in the feed. The thermal stability of the polymers was measured by thermogravimetric analysis in nitrogen. Homopolymers decompose by a one-step mechanism, while copolymers are more thermostable and decompose by a two-step mechanism. Glass transition temperatures (T_gs) of homopolymers are lower than T_gs of copolymers. The number and weight average molecular weights of chlorinated copolymers are higher than those of the corresponding homopolymers.     

The Copolymerization of Alkenes with Maleic Anhydride

The investigations presented deal with the experimental results of the copolymerization of maleic anhydride (MAn) with alkenes. The course of the reaction is explained by the overall rate of the copolymerization (v _Br), which correlates with the solution viscosity of the copolymer, and the dependence of the v _Br maximum on the mole ratio of the monomers at constant total monomer concentration. The use of solvents with increasing donor power leads to increased complexing of the free MAn molecules and of the MAn radical chain ends. The results demonstrate that, for low 1-alkenes, the addition of the MAn chain radical is the rate-determining step of the copolymerization. As the substituents on the olefinic double bond become larger or the double bond shifts to the 1,2-position, the addition of MAn to the hydrocarbon radical becomes more and more the rate-determining step. On the other hand, an increase of the CT complexation of the MAn polymer radical by use of donor solvents decreases the alkene addition rate.