Abstract: Formulation of latex with styrene (St)，potassium persulfate (KPS) and sodium dodecyl sulfate (SDS) was investigated as a function of SDS surfactant concentration [S] to explore its nucleation mechanism. The results showed that micellar nucleation dominated the nucleation process when the concentration of SDS was ≥ 8 mmol/L; while，precipitation nucleation dominated the process at 2mmol/L. From 2mmol/L to 8mmol/L，both micellar nucleation and precipitation worked; and the contribution of micellar nucleation increased with the increase of the concentration of SDS. Additionally，the particle number of latex was calculated：Np∝[S]0.9 when [S] was ≥8mmol/L; Np∝[S]0.8 when 8mmol/L≥[S]≥2mmol/L.

Key words: emulsions, nucleation mechanism, surfactant concentration, particle size distribution

摘要： 以苯乙烯（St）为单体、十二烷基硫酸钠（SDS）为乳化剂、过硫酸钾（KPS）为引发剂，重点研究了该乳液聚合体系中乳化剂浓度（[S]）对胶束成核和沉淀成核的影响规律。结果表明，当SDS浓度高于CMC时（[S]≥ 8mmol/L），体系的成核以胶束成核为主；当[S]=2mmol/L时，体系的成核以沉淀成核为主；当2mmol/L<[S]< 8mmol/L时，体系同时以沉淀成核和胶束成核两种方式成核，且胶束成核所占的比例随着SDS浓度的增加而增大。研究了聚合反应过程中SDS浓度对单位体积水中乳胶粒个数（Np）的影响规律：当[S]≥8mmol/L时，Np∝[S]0.9；当[S]<8mmol/L时，Np∝[S]0.8。

关键词: 乳液, 成核机理, 乳化剂浓度, 粒度分布