无皂乳液聚合法制备亚微米级单分散聚苯乙烯微球

Preparation of Sub-micron Monodisperse Polystyrene Microspheres by Soap-Free Emulsion Polymerization

采用无皂乳液聚合法制备了亚微米级聚苯乙烯（PS）微球，考察了苯乙烯（st）单体浓度、引发剂过硫酸钾（K2S2O2）浓度、离子强度（氯化钠浓度）与Ps微球粒径及其分布的关系。然后通过加入微量乳化剂或肛环糊精对无皂乳液聚合法进行改进，研究了改进效果。结果表明，Ps微球的粒径随st单体浓度和氯化钠浓度的增加而增加、随K2S2O2浓度的增加而减小，通过调节这3种原料的浓度，可制得粒径在450～1000nm且单分散系数小于0．08的Ps微球，但产品收率较低，仅为30％左右。在相同的合成条件下，加入微量乳化剂可制得粒径在100～350nm且单分散系数小于0．05的PS微球，产品收率提高到75％左右；加入微量序环糊精可制得粒径在300nm左右且单分散系数小于0．08的PS微球，产品收率可达80％且反应时间大幅缩短，由原来的12h缩减到5h。

Sub-micron polystyrene （PS） microspheres were synthesized by soap-free emulsion polymerization. Effects of styrene（St） monomer＇ s concentration, potassium persulfate（K2S2Os） initiator＇ s concentration and ionic strength （concentration of sodium chloride ） on particle diameter and distribution of the PS microspheres were studied. Then soap-free emulsion polymerization was improved through adding a small amount of emulsifying agent or fl-cyclodextrin and the improving effects were studied also. The results show that the particle diameter of PS increases with concentrations of St monomer and sodium chloride increasing, decreases with concentration of K2S208 decreasing. The PS microspheres with particle diameter being within 450-1 000 nm and monodisperse coefficient being less than 0.08 can be obtained by adjusting the concentrations of three raw materials mentioned above, but the product yield is low and the value is only about 30%. Under the same synthesis conditions, the PS microspheres with particle diameter being within 100-350 nm and monodisperse coefficient being less than 0.05 can be obtained by adding emulsifying agent, the product yield is improved to about 75%. The PS microspheres with particle diameter being about 300 nm and monodisperse coefficient being less than 0.08 can be obtained by adding fl-cyclodextrin, the product yield can achieve about 80%, moreover, the reaction time is decreased from 12 h to 5 h.