Size control of polystyrene nodules formed on silica particles in soap-free emulsion polymerization with amphoteric initiator
Size control of polystyrene nodules formed on silica particles in soap-free emulsion polymerization with amphoteric initiator
复制标题
DOI：
10.1007/s00396-009-2063-7
复制
发表时间：
2009-09-01
影响因子：
2.4
通讯作者：
Konno, Mikio
中科院分区：
文献类型：
--
作者：
Nagao, Daisuke;Ueno, Takuya;Konno, Mikio
采用 2,2'-偶氮双[N-(2-羧乙基)-2-2-甲基丙脒] (VA-057) 两性引发剂，在 3-甲基丙烯酰氧基丙基三甲氧基硅烷表面改性的二氧化硅颗粒存在下，通过苯乙烯无皂乳液聚合制备覆盆子形复合颗粒。在聚合反应中，溶液的pH值范围为7.9至9.9，以改变引发剂中可电离基团的解离程度。在 8.0 至 9.3 的 pH 范围内获得了覆盆子状颗粒，并且吸附在二氧化硅颗粒上的聚苯乙烯 (PSt) 结节的平均尺寸有随 pH 值降低的趋势。该趋势与在不存在二氧化硅颗粒的情况下在常规无皂乳液聚合中形成的聚合物颗粒的趋势类似。二氧化硅颗粒浓度的增加导致 PSt 结核的最终尺寸减小。减少的原因是固定在二氧化硅表面的聚合物颗粒的稳定性，以防止聚合物颗粒在水相中聚集。
An amphoteric initiator of 2,2'-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was applied to fabrication of raspberry-shaped composite particles in soap-free emulsion polymerization of styrene in the presence of silica particles surface-modified with 3-methacryoxypropyltrimethoxysilane. In the polymerizations, pH of the solution was ranged from 7.9 to 9.9 to alter dissociation degree of ionizable groups in the initiator. Raspberry-shaped particles were obtained in a pH range of 8.0 to 9.3 followed by a tendency in which average size of polystyrene (PSt) nodules adsorbed onto the silica particles decreased with pH. This tendency was similar to that of polymer particles formed in conventional soap-free emulsion polymerization in the absence of the silica particles. An increase in silica particle concentration led to a decrease in the final size in PSt nodules. The decrease was caused by the stabilization of polymer particles fixed to the silica surface against polymer particle aggregation in water phase.