【作者】 唐向阳；

【导师】 于九皋；

【作者基本信息】 天津大学 ， 应用化学， 2006， 博士

【摘要】 合成了二硫代苯甲酸苯乙基酯(CDB)、二硫代苯甲酸异丙苯基酯(PEDB)和二硫代苯甲酸苄基酯(BDB)三种RAFT试剂,利用红外光谱和核磁共振对产物组成进行了表征。以三种RAFT试剂为链转移剂、以偶氮二异丁腈(AIBN)为引发剂,进行了苯乙烯的本体聚合反应,结果表明在所制备的三种RAFT试剂中BDB对苯乙烯本体聚合反应的控制性最好。对聚合动力学和分子量的控制进行了研究。研究表明,此种苯乙烯本体聚合体系具有明显的活性自由基聚合特征。提出了活性自由基聚合的动力学模型并对文献中的理论分子量模型进行了修正。在前述本体聚合研究工作基础上,进一步研究了RAFT存在下苯乙烯无皂乳液聚合。以BDB用作RAFT试剂进行苯乙烯和丙烯酸的本体共聚,制备具有自乳化功能的低聚物。利用所制备的低聚物进行乳化,进行苯乙烯无皂乳液聚合研究。所合成的RAFT共聚物乳化效果好,得到的聚合物乳液体系稳定。研究结果表明要制备稳定的无皂乳液,需要加入三乙胺,所需量为中和80%~100%丙烯酸;加入丙酮有利于低聚物的乳化。在75℃条件下进行聚合反应,无皂乳液聚合反应速率较快,体系稳定。乳液聚合产物的分子量与单体转化率呈线形关系,产物的数均分子量比理论分子量大,随着转化率的增加,分子量分布会变宽。本体共聚配方中BDB/AIBN的比值越大、BDB含量越大,乳液聚合速率越小,相近转化率时产物的分子量越小,分布也越窄。乳液粒的粒径处于250nm~300nm,粒径分布指数为1.335。更多还原

【Abstract】 Cumyl Dithiobenzoate (CDB), 1-Phenylethyl Dithiobenzoate (PEDB)and Benzyl Dithiobenzoate (BDB),there RAFT agents,were synthesized and the structures of the products were determined by IR spectrum and 1H-NMR spectrum .The bulk polymerization of styrene using AIBN as initiator at the presence of a RAFT agent was studied in detail, including the kinetics and control over molecular weight and molecular weight distribution. The results confirmed the distinct living polymerization character of the reaction system and showed that among the three obtained RAFT agents BDB was the best for styrene bulk polymerization system. A mathematic model for the kinetics of the styrene RAFT bulk polymerization was set up and modification to the model of molecular weight reported in literatures was made.On the basis of the above bulk polymerization, further study on emulsifier-free emulsion polymerization of styrene with the presence of RAFT was made. Firstly, the RAFT BDB was used for preparation of styrene-acrylic acid RAFT oligomer by bulk polymerization,which has function a self emulsification. The so prepared RAFT copolymer was then employed in followed study on emulsion polymerization of styrene without using any extra surfactant. Polymer Emulsion products of good stability were obtained by this access.According to the experiment work, for the preparation of stable soap-free polymer emulsion, triethylamine is needed to neutralized 80~100% of the acylic acid used. The use of acetone is benifitial to the emulsification of the oligomer. At temperature of 75°C, the reaction could proceed faster and thus led to a stable product. The molecular weight of the polymer product showed a linear relationship with the monomer conversion. And the real molecular weight was higher than the theoretical calculation. With a higher monomer conversion, the molecular weight distribution became broader. In the work, the higher ratio更多还原