有机硅改性丙烯酸酯乳液的合成及性能研究

采用有机硅氧烷与丙烯酸酯单体共聚制备有机硅改性丙烯酸酯乳液,研究了有机硅单体用量、乳化剂配比和温度等因素对乳液的影响,并对涂膜性能进行了测试。研究结果表明,有机硅与丙烯酸酯单体能很好地聚合,且制备出的乳液性能优异,可以作为高性能外墙涂料的基体树脂。     

有机硅-丙烯酸酯弹性乳液的制备与研究

采用有机硅氧烷与丙烯酸酯单体共聚制备有机硅改性丙烯酸酯弹性乳液,研究了有机硅单体、乳化剂用量及配比等因素对乳液的影响,并对涂膜进行了兀'一IR表征.研究结果表明有机硅与丙烯酸酯单体能很好地聚合,且制备出的乳液性能优异,可以作为高性能外墙弹性涂料的基体树脂.     

有机硅、云母改性丙烯酸酯互穿网络阻尼材料的制备及性能研究

采用半连续乳液聚合的方法,在以丙烯酸酯类单体为主的二元互穿网络中加入有机硅单体与乳液进行共聚,得到了性能稳定的有机硅丙烯酸酯共聚乳液,并在乳液中加入了无机填料(绢云母)。考察了有机硅单体的用量对合成乳液及其胶膜性能的影响,通过红外光谱分析,证明了有机硅单体和丙烯酸酯单体的共聚。通过透射电镜(TEM)对乳胶粒子的观察,分析了有机硅单体及云母对乳液乳胶粒子形态结构的影响。通过动态粘弹仪(DMA)对材料的动态力学性能进行测试得到,Tanδ>0.3的温度范围为:-65～150℃。     

有机硅-丙烯酸酯乳液的稳定性研究进展

根据国内外制备性能稳定的有机硅-丙烯酸酯乳液的研究进展,从有机硅-丙烯酸酯乳液的聚合机制角度,分析了聚合工艺、聚合温度、乳化剂、体系p H和有机硅单体等因素对有机硅-丙烯酸酯乳液稳定性的影响。提出了提高有机硅-丙烯酸酯乳液稳定性的方法,并对今后研究的重点进行了展望。     

有机硅改性丙烯酸乳液性能的研究

采用含乙烯基官能团的有机硅单体与甲基丙烯酸酯、丙烯酸酯和丙烯酸羟基酯等单体通过种子乳液聚合方法进行共聚,合成了有机硅改性丙烯酸酯共聚乳液,考察了有机硅单体用量对乳液机械稳定性、热稳定性、电解质稳定性和冻融稳定性的影响,同时还考察了乳液胶膜的机械性能和吸水率改进。     

有机硅树脂-聚丙烯酸酯接枝共聚物的研究

通过在有机硅聚合物的分子链上接枝聚丙烯酸酯支链的方法,制备出有机硅-丙烯酸酯接枝共聚树脂。对有机硅母体的制备、接枝混合单体的配比、丙烯酸酯与有机硅聚合物母体的比例、接枝单体加料方式等对有机硅共聚物性能的影响等问题进行了研究。     

有机硅改性的涂料印花粘合剂的研制

通过有机硅对丙烯酸酯进行改性 ,合成了一种性能优良的涂料印花粘合剂 ,并对丙烯酸酯单体的选择及配比、有机硅单体的选择及用量、反应性单体的选择与用量、乳化剂的配比及用量进行了研究。     

高性能改性丙烯酸酯乳液及其涂料的研制

研究了有机硅单体与丙烯酸类单体的乳液聚合反应，制备出高性能的改性丙烯酸酯乳液。主要讨论了乳化剂、引发剂、有机硅加入方式及用量对乳液性能的影响。用有机硅改性丙烯酸酯乳液制成的涂料具有优越的耐水性，其耐洗刷性达60000次。     

烯烃基碳硅氧烷树枝状大分子单体及其应用

概述了烯烃基碳硅氧烷树枝状大分子单体的结构,介绍了层级为1和层级为2的烯烃基碳硅氧烷大分子单体的合成方法及结构表征,以及烯烃基碳硅氧烷树枝状大分子单体在有机聚合物改性及化妆品领域的应用,如:与有机单体溶液共聚制备有机硅改性共聚物、与丙烯酸酯单体乳液共聚制备有机硅改性丙烯酸酯乳液、与长链烷基丙烯酸酯共聚制备化妆品成膜剂、与甘油或木糖醇共改性制备亲水性有机硅交联共聚物等。     

高性能改性丙烯酸酯乳液的制备

研究了有机硅单体与丙烯酸类单体的乳液聚合反应,制备出高性能的改性丙烯酸酯乳液。主要研究了乳化剂、引发剂、有机硅加入方式及用量对乳液性能的影响,用有机硅改性丙烯酸酯乳液制成的涂料具有优越的耐水性,其耐洗刷性达4万次。     

超浓乳液聚合氧化还原引发体系的研究进展

介绍了超浓乳液的三个主要特点。从体系状态,单体含量,聚合速度,相对分子质量,聚合物形态和设备利用率方面比较了超浓乳液聚合与传统乳液聚合及本体聚合的区别。指出超浓乳液聚合中使用热分解引发剂所产生的问题及使用氧化还原引发剂的原因。还简单介绍了氧化还原引发体系的分类,回顾了前人在超浓乳液聚合工作中不同单体体系使用的氧化还原引发剂的情况,总结了不同单体体系中氧化剂还原剂的最佳配比,以及它们对动力学、相对分子质量的影响。最后展望了超浓乳液聚合新的发展方向。     

微悬浮聚合法合成聚醋酸乙烯酯的动力学研究

采用微悬浮法合成聚醋酸乙烯酯,对其聚合反应的动力学进行了研究。考察了引发剂浓度、乳化剂浓度、单体浓度以及温度对聚合反应速率的影响。结果表明,聚合反应速率对引发剂浓度、乳化剂浓度和单体浓度的反应级数分别为0．45,0．28,1．90,单体浓度对聚合反应速率的影响最大,反应体系的表观活化能为105．96 kJ/mol。     

Semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion

The semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion was studied under the condition of no seed particles used in polymerization system. Concentration of emulsifier was set above critical micelle concentration. Effect of monomer feed rate on the chemical kinetics, average particle size and distribution and on the polymer molar mass and distribution was investigated. During monomer addition, polymerization rate was constant and controlled by the monomer feed rate. According to the proposed mechanism for anionic polymerization in emulsion, it was assumed that also the number of active polymerization sites and monomer concentration at the particle surface, where propagation occurs, remain constant. A continuous increase of average particle size and absence of extensive condensation reactions at high conversion suggested that the freshly added monomer diffuses toward hydrophobic polymer particles, where it is consumed in propagation reaction and/or accumulated in the particle core.     

乳液聚合中保护胶体的研究进展

介绍了乳液聚合中保护胶体稳定聚合物乳液的机理,详细综述了保护胶体在乙烯基单体、共轭烯单体和丙烯酸酯类单体乳液聚合中的研究进展。指出了单体在保护胶体上的适量接枝是乳胶粒稳定的必要条件,因此,合理使用保护胶体在乳液聚合中有重要意义。     

等离子体引发炭黑 接枝聚合的溶剂效应

用等离子体处理炭黑发现,这些等离子体黑颗粒经辉发放电后会产生不同种类的活性种,如高能电子、光子、自由基等,这些活性能引发乙烯基单体进行接枝聚合反应。等离子体炭黑对不同的乙烯基单体具有较强的选择性,当选用不同的溶剂时会产生明显的溶剂效应,产生溶剂效应的原因与等离子体引发聚合的机理有关。等离子体的位阻排斥引发机理会对乙烯基单体的接枝聚合产生较强的选择性。等离子体的溶剂化活性引发机理会对乙烯基单体的接枝聚合产生较强的溶剂效应。当等离子体炭黑与甲基丙烯酸甲脂、甲基丙烯酸丁酯接枝聚合时,溶剂采用二甲基甲酰胺,可得到较高的树枝率。同时讨论了接枝反应的的影响因素。在炭黑颗粒上接枝不同的乙烯基单体会对炭黑体系的分散稳定性产生不同的影响。     

聚丙烯酸酯乳液型压敏胶的聚合方法研究

采用三种乳液聚合方式：间歇乳液聚合法、半连续乳液聚合法、种子乳液聚合法,根据实验结果和三种聚合工艺的特点,选出最适合的丙烯酸酯聚合方式;探讨了聚合温度、搅拌强度、软硬单体配比、功能单体、引发剂等因素对聚合反应及压敏胶性能的影响。研究结果表明：种子乳液聚合法最佳;当体系聚合温度为80℃,聚合反应6h,搅拌速率为200f／min时可得到综合性能较好的压敏胶;当软硬单体的比例大约为3：1时,压敏胶可达到最大剥离强度;引发剂的适宜用量为单体总量的0．5％。     

Late Transition Metal Catalyst Based on Cobalt for Polymerization of Ethylene

The late transition metal catalyst of [2,6-diacethylpyridinebis(2,6-diisopropylphenylimine)]cobalt(II) dichloride was prepared under controlled conditions and used for polymerization of ethylene. Methylaluminoxane (MAO) and triisobuthylaluminum (TIBA) were used as a cocatalyst and a scavenger, respectively. The highest activity of the catalyst was obtained at about 30°C; the activity decreased with increasing temperature. At polymerization temperatures higher than 50°C not only was a sharp decrease in the activity observed but also low molecular weight polyethylene product that was oily in appearance was obtained. The polymerization activity increased with increasing both of the monomer pressure and [MAO]:[Co] ratio. However, fouling of the reactor was strongly increased with increasing both of the monomer pressure and the amount of MAO used for the homogeneous polymerization. Hydrogen was used as the chain transfer. The activity of the catalyst and the viscosity average molecular weight (M_v) of the polymer obtained were not sensitive to hydrogen concentration. However, the viscosity average molecular weight of the polymer decreased with the monomer pressure. The (M_v), the melting point, and the crystallinity of the resulting polymer at the monomer pressure of 1 bar and polymerization temperature of 20°C were 1.2 × 10⁵, 133°C, and 67%, respectively. Heterogeneous polymerization of ethylene using the catalyst and the MAO/SiO₂ improved morphology of the resulting polymer; however, the activity of the catalyst was also decreased. Fouling of the reactor was eliminated using the supported catalyst system.     

超临界二氧化碳中丙烯酸乙酯/3-氯丙烯接枝天然橡胶的合成与表征

采用超临界二氧化碳溶胀聚合法,以丙烯酸乙酯（EA）/3-氯丙烯（AC）为单体对天然橡胶进行了接枝改性,合成了接枝共聚物NR-g-(EA/AC)。考察了压力和引发剂用量对接枝聚合反应的影响;对NR-g-( EA/AC)进行了红外光谱、力学性能、耐溶剂性、耐燃性、硬度的测试及接枝效率和接枝率的计算,并与溶液聚合法所得NR-g-( EA/AC)的性能进行了比较。结果发现,在接枝橡胶中成功的引入了—C=O和—Cl基团;接枝橡胶的弹性模量、拉伸强度、硬度、耐燃性和耐溶剂性较天然橡胶的有了显著提高。使用溶液法和超临界二氧化碳溶胀聚合法改性天然胶乳都获得了较高的转化率和接枝率,所得产品的机械力学性能相近,但溶液法所得产品的耐溶剂性能优于后一种方法。由于超临界二氧化碳的绿色溶剂性质,超临界二氧化碳溶胀聚合法有望取代溶液聚合法而发展成一种绿色的接枝改性天然橡胶方法。     

Surface functionalization of Si3N4 nanoparticles by graft polymerization of glycidyl methacrylate and styrene

To improve dispersibility and interfacial interaction of nano‐Si₃N₄ particles in epoxy‐based composites, graft of glycidyl methacrylate (GMA) and styrene (St)/GMA onto the nanoparticles' surface was carried out in terms of emulsion polymerization method. The grafting polymers proved to be chemically attached to the nanoparticles via the double bonds introduced during the coupling agent pretreatment. The factors affecting the graft parameters, such as monomer concentration, initiator consumption, reaction time, etc., were investigated. It was shown that higher concentrations of monomer and initiator are favorable for the graft polymerization. When St/GMA was employed as the grafting monomer, the nanoparticles were found to play the role of polymerization loci. The grafted nanoparticles exhibit greatly improved dispersibility in cured epoxy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 992–999, 2006     

Anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion above critical micelle concentration

Batch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion using nonionic and cationic emulsifiers was studied. The concentration of emulsifiers was set above their critical micelle concentration. Effects of emulsifier concentration, nonionic/cationic emulsifier ratio and cationic emulsifier/initiator (KOH) ratio on the kinetics, average particle size and distribution and on the average molecular weight and distribution were investigated and discussed. At the beginning of the polymerization, empty micelles, active micelles (polymer particles) and monomer droplets co-exist in emulsion. The transport of monomer from monomer droplets toward empty micelles was confirmed by monomer droplets and empty micelles disappearance and by formation of smaller particles. The transport of monomer from monomer droplets toward polymer particles was not confirmed, since the average polymer particle size did not increase during polymerization. It was proposed, that at lower conversions, monomer diffuses from polymer particle interior to particle surface, while at higher conversions, the monomer diffuses from larger to smaller polymer particles. Emulsifier concentration, nonionic/cationic emulsifier ratio and cationic emulsifier/KOH ratio have an evident effect on the kinetics and on the average molecular weight, thus demonstrating that cationic emulsifier participates to the initiation reaction.