Abstract:

The evolution of particle size and the ratio of particle number (N_p) and droplet number (N_d) of the mini-emulsion copolymerization of γ-methacryloxy propyl trimethoxysilane (MPS) and styrene (St) were investigated.The droplet and particle size were measured by dynamic light scattering (DLS).The individual conversion of St was followed by gas chromatography, and the overall conversion was measured by gravimetry.The surface tension of the mini-emulsion was measured with the plate method using Krüss processor tensiometer.With the increase of the ratio of MPS to St, the size of mini-droplets decreased gradually due to the decrease of the interfacial tension between oil and aqueous phase.The evolution of particle size and N_p/N_d were tightly dependent on the nature of initiators.The particle size of the system initiated by KPS increased and N_p/N_d decreased in the process of polymerization which could be ascribed to the increase of the formation of hydrogen bonding between particles due to the existence of the extending polymer chain with silanol groups on the interface of the latexBecause the radicals were mainly produced in the latex, the particle size of the system initiated by AIBN nearly kept constant in the process of polymerization.With the increase of the MPS/St [JP+3]ratio, the particle size increased, but N_p/N_{d }decreased, which could be attributed to the decrease of adsorption ability of the surfactant on the latex and the increase of the formation of hydrogen bonding between particles as a result of the increase of hydrolysis resultants.The value of N_p/N_d was independent of the amount of surfactant and HD.The sizes of initial mini-emulsion in acidic and basic conditions were much lower than that in neutral condition.However, as the polymerization proceeded, the particle size under acidic and basic conditions increased and the particle number decreased rapidly.It was worthwhile to note that the final products in acidic and basic conditions were still emulsion.

Key words:

细乳液共聚合, 杂化粒子, 甲基丙烯酸3-三甲氧基硅丙酯, 稳定性

摘要：

研究了各聚合条件对甲基丙烯酸3-三甲氧基硅丙酯（MPS）和苯乙烯（St）细乳液共聚合体系乳胶粒稳定性的影响，聚合条件包括引发剂类型、MPS/St比例、乳化剂用量、共稳定剂用量和体系pH值。通过动态激光光散射测定初始液滴和乳胶粒的尺寸，气相色谱测定苯乙烯的转化率，总转化率由重量法测定。研究发现，油溶性引发剂偶氮二异丁腈（AIBN）引发的体系，MPS/St比例为1∶4时，聚合过程中乳胶粒尺寸基本不变，最终乳胶粒数与初始液滴数比值为0.97。相同MPS/St比例，水溶性引发剂过硫酸钾（KPS）引发的体系，随聚合反应进行乳胶粒尺寸增加，最终乳胶粒数和初始液滴数比值仅为0.55，乳胶粒发生明显聚并。随MPS/St比例增加，乳胶粒稳定性变差，乳化剂和共稳定剂量变化对乳胶粒数和初始液滴数比值影响不大。在酸性或碱性介质中，由于水解反应加剧，乳胶粒聚并严重，最终粒子数只占初始粒子数的0.25。

关键词:

细乳液共聚合, 杂化粒子, 甲基丙烯酸3-三甲氧基硅丙酯, 稳定性