丙烯酰胺/丙烯酸/甲基丙烯酸甲酯双水相共聚过程的临界分相

采用偶氮二异丙基咪唑啉盐酸盐（VA-044）引发丙烯酰胺（AM）/丙烯酸（AA）/甲基丙烯酸甲酯（MMA）在含一定量聚丙烯酸钠（PAANa）的硫酸铵（AS）水溶液中进行双水相共聚合。用分光光度计对聚合体系分相进行在线确定,采用溴化法测定了聚合体系临界分相时的转化率,用凝胶渗透色谱（GPC）对聚合体系临界分相时聚合物链的分子量进行了研究。随着MMA用量的增加,临界分相转化率和临界分相分子量逐渐减少;AM与AA单体总量增加,临界分相转化率逐渐降低,临界分相分子量逐渐变大;相似文献   

甲基丙烯酸甲酯对阳离子型丙烯酰胺双水相共聚合过程的影响

以2,2’-偶氮二异丙基咪唑啉二盐酸盐(VA-044)为引发剂,在聚乙二醇(PEG)水溶液中采用双水相聚合法进行了丙烯酰胺(AM)/甲基丙烯酰氧乙基三甲基氯化铵(DMC)/甲基丙烯酸甲酯(MMA)的三元共聚合,与AM/DMC共聚进行对比,系统研究了疏水单体MMA在双水相聚合过程中所起的作用。通过紫外分光光度计在线检测双水相聚合的相分离过程,发现当MMA浓度增大时,分相时的临界转化率和临界分子量均减小,说明MMA具有促进相分离的功能。通过改进溴化法确定单体转化率,发现MMA能加速双水相聚合反应速率。通过旋转黏度计测试聚合体系的表观黏度,发现MMA的引入会增大体系的表观黏度。通过激光粒度仪检测聚合体系的液滴尺寸及分布,发现MMA能加快聚合物液滴的成长。     

甲基丙烯酸甲酯与降解天然橡胶胶乳共聚的研究

研究了不同降解程度的天然橡胶胶乳与甲基丙烯酸甲酯 (MMA)共聚反应 ,发现随着降解时间增长 ,共聚物中 MMA聚合链与橡胶段的相对比例 (重量比 )明显增加。找到了一种适用于降解胶乳与 MMA共聚混合物的分离方法     

降解天然橡胶胶乳与甲基丙烯酸甲酯共聚的研究

研究不同降解程度的天然橡胶胶乳与甲基丙烯酸甲酯（ＭＭＡ）共聚反应，找到了一种适用于降解胶乳与ＭＭＡ共聚混合物的分离方法，发现随着降解时间的增长，共聚物中ＭＭＡ聚合链段与橡胶链段的相对比例（重量比）明显增加。     

新型丙烯酸共聚材料

英国的Distmpol公司日前工业化生产一款新型透明坚韧的丙烯酸共聚物,该产品商标属于NAS和Zyla系列。这款新型FDA批准的材料是传统热塑性塑料的有益替代品,可替代聚碳酸酯（PC）、聚甲基丙烯酸甲酯（PMMA）、透明聚苯乙烯（PS）以及透明丙烯腈．丁二烯一苯乙烯共聚物（ABS）。     

交联甲基丙烯酸甲酯/丙烯酸共聚微球羧基分布研究

用分散聚合法制备了交联甲基丙烯酸甲酯/丙烯酸(PMMA/AA)共聚微球,以电导滴定法研究了不同聚合反应条件对微球不同区域羧基分布的影响。研究结果表明增大配方中丙烯酸浓度或引发剂浓度,表面结合与被包埋的羧基含量增大,游离羧基含量降低;提高反应温度,表面结合羧基含量减小,被包埋的与游离羧基增大。 采用分散聚合法制备了交联甲基丙烯酸甲酯/丙烯酸(PMMA/AA)共聚微球,以电导滴定法研究了不同聚合反应条件对微球不同区域羧基分布的影响。研究结果表明增大配方中丙烯酸浓度或引发剂浓度,表面结合与被包埋的羧基含量增大,游离羧基含量降低;提高反应温度,表面结合羧基含量减小,被包埋的与游离羧基增大。     

反相乳液法芋头淀粉/丙烯酸/丙烯酰胺接枝共聚

通过吸水倍率的测定研究了各反应因素对反相乳液体系中芋头淀粉-丙烯酸-丙烯酰胺的接枝聚合反应的影响。结果表明:反应温度60℃,单体中和度70%,油水比1.3∶1,交联剂用量0.06 g,引发剂用量1.0 g,反应时间2.5 h时,产物树脂吸水倍率达到了129 g/g,具有较快的吸水速率和较强的再生能力。     

低分子量丙烯酰胺—丙烯酸共聚物的研制

论述了过硫酸钾－亚硫酸氢钠氧化还原引发剂引发丙烯酰胺与丙烯酸水溶液共聚合反应工艺,得出了合成低分子量丙烯酰胺－丙烯酸共聚物的最佳工艺条件为：引发剂温度２５℃,丙烯酰胺浓度３．５ｍｏｌ／Ｌ,丙烯酸浓度０．７ｍｏｌ／Ｌ,过硫酸钾浓度０．００１１ｍｏｌ／Ｌ,过硫酸钾浓度０．００１１ｍｏｌ／Ｌ,亚硫酸氢钠浓度０．００２９ｍｏｌ／Ｌ,溴化铜浓度０￣０．０００４５ｍｏｌ／Ｌ。     

丙烯酸/2—丙烯酰胺基—2—甲基丙磺酸共聚物的合成

以丙烯酸（AA）、2－丙烯酰胺基－2－甲基丙磺酸（AMPS）为原料，合成了一种水溶性共聚物阻垢剂。测定了共聚物的阻垢分散性能；探讨了单体配比、反应温度、分子量调节剂等对共聚物阻垢性能的影响。     

丙烯酸/环氧树脂共聚可制优异水性涂料

摘自：www．china—coating．net 丙烯酸／环氧树脂接枝共聚物可以制备优异的水性涂料。接枝共聚就是通过丙烯酸类单体与环氧树脂接枝共聚反应,在环氧树脂中引入强亲水性基团-COOH,使树脂水性化。郑州大学工学院化工学院最近研究了新的丙烯酸／环氧树脂共聚接枝方法,     

Synthesis of monodisperse styrene/methyl methacrylate/acrylic acid latex using surfactant‐free emulsion copolymerization in air

Monodisperse styrene/methyl methacrylate/acrylic acid (St/MMA/AA) copolymer microspheres have been prepared with surfactant‐free emulsion polymerization in air. The presence of oxygen in the system not only caused an induction period but also decreased the average particle size (D_p). However increasing AA concentration ([AA]) gave a reduction in the induction period. The FTIR and NMR analysis of the latex copolymer confirmed that the correlation of the copolymer compositions with the feed compositions was much better at the lower [AA] than at the higher levels. The AA contents of the copolymers obtained in air were much lower than those of the copolymers obtained under N₂ protection. Decreasing [AA] led to decrease in the copolymer molecular weight and broadening of the molecular weight distribution, but the particle size distribution (δ/D_p) was unaffected. In addition, the average particle diameter (D_p) was proportional to [AA]^–0.255, and increasing comonomers feed content caused linear increase of D_p, and a monodisperse sample with final solids contents up to 34.2 wt % was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dispersion copolymerization of acrylamide with acrylic acid in an aqueous solution of ammonium sulfate: Synthesis and characterization

Dispersion copolymerization of acrylamide with acrylic acid in an aqueous solution of ammonium sulfate using poly(2‐acrylamido‐2‐methylpropanesulfonic acid sodium) as the stabilizer and ammonium persulfate (APS) as the initiator was investigated. The influence of initiator concentration, stabilizer concentration, ammonium sulfate concentration, chain‐transfer agent concentration, and polymerization temperature on the copolymerization was discussed. The results showed that varying the ammonium sulfate concentration could affect the particle size and the intrinsic viscosity of the copolymer significantly. With increasing the stabilizer concentration, the particle size of the copolymer decreased first, and then increased, meanwhile the intrinsic viscosity of the copolymer decreased. The increase of initiator concentration, chain‐transfer agent concentration, and polymerization temperature resulted in the increase in the particle size. Polydisperse spherical particles were formed in the system, and the kinetics for the dispersion copolymerization were discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3685–3690, 2006     

Mechanism of the droplet formation and stabilization in the aqueous two‐phase polymerization of acrylamide

Aqueous two‐phase polymerization of acrylamide has been carried out in an aqueous solution of poly(ethylene glycol) initiated by ammonium persulfate. The chemical composition of the product was characterized by FTIR, and the droplet size distribution in the initial stage of the polymerization was followed by dynamic light scattering. On the basis of the evolution of polyacrylamide aqueous droplets size distribution and morphology at every stage, a new mechanism of droplet formation was proposed. The experimental phenomenon that the small droplets always existed in the process of polymerization and some irregular shape droplets were formed in the product of aqueous two phase polymerization could be successfully explained by the new mechanism. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

甲基丙烯酸甲酯/丙烯酸/水反相无皂微乳液体系的聚合

采用滴定法描绘了甲基丙烯酸甲酯（MMA）/丙烯酸（AA）/H₂O无皂微乳液体系的三元相图,用电导率法对单相微乳液区域进行了类型划分.在相图研究的基础上,考察了引发剂（AIBN）用量、体系AA含量和水含量对MMA/AA/H₂O反相无皂微乳液体系聚合速率的影响.结果表明,聚合速率随引发剂用量和AA含量的增加逐步加快,随体系水含量的提高出现极大值.得到动力学关系,表明AA的乳化促进作用显著,聚合在连续相进行的同时亦在分散相液滴内进行.此外,环境扫描电镜的测试结果表明,所得聚合产物具有明显的孔穴结构.     

Composition control through pH and ionic strength during acrylic acid/acrylamide copolymerization

The possibility of controlling the composition of acrylic acid/acrylamide copolymers by controlling the pH and the ionic strength of the reaction medium is investigated. The reactivity ratios of charged monomers depend on the pH of the medium, acrylic acid is the more reactive monomer below pH 3 and acrylamide above pH 4. The working pH was set at 3.6, a candidate for the crossover point, where no composition drift is expected. Copolymerization kinetics is investigated at this pH at various ionic strengths and a reaction without composition drift up to 80% conversion was achieved. All the chains produced in this reaction contain 30% ± 3% acrylic acid. Copolymer conversions, molecular weights, and composition distributions were measured through Automatic Continuous Online Monitoring of Polymerization (ACOMP) system. The copolymerization data were analyzed by a recent error in variables method (EVM) and reactivity ratios are calculated. The results show that in salt free conditions, the reactivity ratios depend on the ionic monomer concentration (ionic strength) in addition to the pH of the reaction medium. The effect of polyelectrolytic interactions on the reactivity ratios and the resulting composition drift during the reaction, sequence length distribution, and Stockmayer bivariate distribution are discussed in detail. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

苯乙烯和甲基丙烯酸甲酯梯度共聚物的应用

将用原子转移自由基聚合及连续补加甲基丙烯酸甲酯（MMA）的方法制备的苯乙烯（St）/MMA梯度聚合物P（Pt-t-MMA）作为增容剂应用于聚氯乙烯/苯乙烯-丁二烯-苯乙烯嵌段共聚物（PVC/SBS）和PS/PMMA聚合物合金的增容和改性。扫描电镜结果表明,P（St-t-MMA）可以改善PVC/SBS和PMMA/PS合金的相容性。PVC/SBS合金中加入少量P（St-t-MMA)后,冲击强度从6.0kJ/m^2提高到12.1kJ/m^2,加工流变性能得到了改善。SBS用量也影响PVC/SBS合金的冲击强度。     

Unimolecular-micelle formation of poly(methyl methacrylate)-graft-polystyrene in iso-amyl acetate

By means of light scattering, unimolecular-micelle formation is investigated for poly(methyl methacrylate)- graft-poly(styrene)s with different graft-chain densities in a dilute solution of a selective solvent. Molecular weights of the poly(methyl methacrylate) (PMMA) backbone and the branch poly(styrene) (PS) are about 6 × 10⁶ and 9 × 10³, respectively, and the graft-chain density is relatively low, ranging from 6 to 17 of PS composition in wt%. The solvent used is iso-amyl acetate, which is a thermodynamically good solvent for PS and a poor solvent (θ-temperature: 60°C) for PMMA. Radius of gyration, hydrodynamic radius, and the second virial coefficient are measured as a function of temperature ranging from 10 to 70°C. At a branch PS composition of 6 wt%, with decreasing temperature, the copolymer chain shrinks in the same manner as the PMMA chain with no PS branches, although the θ-temperature decreases by about 25°C. This indicates that no particular order structure is formed. At higher branch densities, rod-like unimicelles are strongly suggested to be formed by intramolecular segregation between the PMMA backbone and PS branches, with the shrunken PMMA backbone forming the core rod covered with PS chains. With decreasing temperature, the dimension of the unimolecular micelle decreases probably due to decreasing contour length of the micelle core.     

Graft copolymerization of mixtures of acrylic acid and acrylamide onto polypropylene film

Liquid phase ultraviolet irradiation in the presence of benzophenone as a photosensitizer and barium hydroxide as a pH controller were used to graft the mixtures of acrylic acid and acrylamide to a polypropylene surface. The surface of the grafted polypropylene samples were characterized by Fourier transform infrared spectroscopy‐attenuated total reflectance, electron spectroscopy for chemical analysis, scanning electron microscopy, and a contact angle meter. The pH value of the reaction medium that produced the graft with equal molar ratio was found to be ∼ 3.77. The optimal reaction condition was found at a monomer feed of 25%, a reaction time of 30 min, and a benzophenone concentration of 1%. Surface tension of the samples increased to a value of 40 dyn cm⁻¹ due to the graft of the hydrophilic monomers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 251–256, 1999