Growth mechanism of soap-free polymerization of styrene investigated by AFM.
Growth mechanism of soap-free polymerization of styrene investigated by AFM.
复制标题
DOI：
10.1016/j.jcis.2005.10.025
复制
发表时间：
2006-05
影响因子：
9.9
通讯作者：
Tetsuya Yamamoto;M. Nakayama;Y. Kanda;K. Higashitani
中科院分区：
文献类型：
--
作者：
Tetsuya Yamamoto;M. Nakayama;Y. Kanda;K. Higashitani
为了阐明无皂聚合过程中聚苯乙烯（PSL）颗粒的生长机理，采用原子力显微镜（AFM），在分子尺度上研究了颗粒和悬浮在本体中的聚合物材料的特性，其中阳离子引发剂V-50使形成的聚合物材料在取样时转移到云母板上.我们主要关注的是在PSL颗粒的生产中，颗粒尺寸随着引发剂浓度的增加而增加的原因。结果表明：（1）由于引发剂的分解速度慢，引发剂和单体在本体溶液中的存在，使聚合物材料在本体溶液中不断生成; (2)在老化0.75 h的早期阶段，颗粒的增长被认为主要是由于从本体中吸收单体而引起的颗粒溶胀。在中间阶段的快速增长是由于在颗粒表面上的本体中的聚合物材料的沉积和它们的本体中的单体的同时溶胀。(3)粒径随引发剂浓度增加而增加的原因是生长过程受本体中聚合物材料的沉积速率控制，其量随引发剂浓度增加。(4)引发剂和单体的相对浓度决定了聚合物的粒径和表面光滑度。
To clarify the growth mechanism of polystyrene (PSL) particles in the soap-free polymerization, characteristics of not only particles but also polymeric materials floating in the bulk were investigated on the molecular scale by using atomic force microscope (AFM), where a cationic initiator V-50 is used to make the formed polymeric materials transfer on the mica plate in sampling. Our main attention here is to know the reason why the particle size increases with increasing initiator concentration in the production of PSL particles. The following are found. (1) As far as the initiators and monomers remain in the bulk solution, the polymeric materials are born in the bulk continuously, because of the slow decomposition rate of initiators. (2) The growth of particles at the early stage of tr⩾0.75 h is considered to be attributable mainly to the particle swelling by absorbing monomers from the bulk. The rapid growth at the intermediate stage is due to the deposition of polymeric materials in the bulk on the particle surface and their simultaneous swelling by monomers in the bulk. (3) The reason why the particle size increases with increasing concentration of initiator is that the growth process is controlled by the deposition rate of polymeric materials in the bulk whose amount increases with the initiator concentration. (4) The particle size and the smoothness of particle surface depend on the relative concentration of initiators and monomers remained.