PHMS为助稳定剂的苯乙烯细乳液聚合过程研究

Study of Miniemulsion Polymerization of Styrene Co-stabilized by Hydrogen-Containing Polysiloxane

以含氢聚硅氧烷(PHMS)为助稳定剂,研究苯乙烯(St)细乳液聚合。考察了细乳液聚合过程中粒子粒径及粒径分布的变化;PHMS用量对单体液滴数目(Nmi)和PSt乳胶粒子数目(Npf)的影响,初步探讨了体系成核机理;并用透射电镜(TEM)观察了PSt乳胶粒子形态。结果表明:PHMS用量由5%增加到20%时,单体液滴粒径先减小后增大,粒径分布在0.211～0.272之间;乳胶粒子粒径由85.97nm减小到72.65nm,粒径分布在0.043～0.098之间;而Npf/Nmi数值在1.46～2.10之间。当PHMS用量为10%(wt)、15%(wt)时,PSt乳胶粒子形态规整匀称,粒径分布较窄。通过以上分析认为PHMS可以作为细乳液聚合的助稳定剂;聚合体系中除单体液滴成核外,还存在均相成核。

The hydrogen-containing polysiloxane（PHMS） was used as the sole co-stabilizer in styrene（St） miniemulsion polymerization.The effects of PHMS concentration on the particle diameter,particle size distribution,number of droplets（Nmi） and number of latex particles（Npf） were investigated.Particle morphologies of the latexes prepared were observed by transmission electron microscopy（TEM）.According to the ratio of Npf and Nmi,the mechanism of particle nucleation during miniemulsion was discussed.The results show that,with the increase of PHMS concentration from 5%（wt） to 20%（wt）,the droplets diameter（dm） reduces firstly and then increases,the indexes of droplet size distribution are between 0.231 and 0.272;the latex particle diameter（dp） reduces from 85.97 nm to 72.65 nm,and the indexes of latex particle size distribution are between 0.043 and 0.098.The ratios of Npf and Nmi are between 1.46 and 2.10.The TEM photographs show that the shapes of latex particles prepared separately with PHMS concentrations of 10%（wt） and 15%（wt） are regular,and the particle size distribution is narrow.Through the analysis above,the conclusion could be made that the PHMS can be used as co-stabilizer for miniemulsion polymerization of styrene,and in the polymerization system,besides the droplet nucleation,there exists the homogeneous nucleation.