氧化-还原低温引发苯乙烯/丙烯酸丁酯细乳液聚合粒度分布和成核机理的研究

用氧化还原引发剂(NH₄)₂S₂O₈/NaHSO₃研究了苯乙烯(St)/丙烯酸丁酯(BA)低温下的细乳液共聚合,细乳液单体液滴在亚微米级(100～400nm).测定了聚合过程中粒子大小及分布的变化,发现细乳液聚合随引发剂、乳化剂和共乳化剂浓度的增加,乳胶粒子尺寸变小,分布变宽,并且比相同条件下传统乳液聚合的粒子大.计算了聚合过程中粒子数变化规律及乳化剂覆盖率,讨论了细乳液与传统乳液中引发剂、乳化剂对反应过程的影响及成核机理的差异.

Studies on Particle Size Distribution and Nucleation Mechanism of St/BA Miniemulsion Polymerization with Redox Initiators

Miniemulsion copolymerization of styrene/butyl acrylate was investigated by redox initiator(NH₄)₂S₂O₈/NaHSO₃ at lower temperature and contrasted it to convention emulsion polymerization. Monomer droplet of the former is several ten times of microns(5~20 μm), and that the latter is in the range of submicron(100~400 nm). The change of particle size and distribution in polymerization process were determined in miniemulsion polymerization process. It is fuond that the particle size decreased with increasing of surfactant, cosurfactant, initiator concentration, but the distribution became wider. In addition, it is bigger than convention emulsion polymerization. The changes rule of particle number and the surfactant-covering ratio were calculated. The effects of initiator and emulsifier on polymerization process and the difference of nucleation mechanism between miniemulsion and conventional emulsion were discussed.