P(St-EA-VTMS)的合成及聚合反应动力学研究

为了提高苯乙烯（St）-丙烯酸乙酯（EA）共聚物的热性能，以St、EA和乙烯基三甲氧基硅烷（VTMS）为单体，十二烷基硫酸钠和辛基酚聚氧乙烯醚为复合乳化剂，通过乳液聚合法制备了含有机硅氧烷的共聚物。用红外光谱仪和热重分析仪对共聚物进行了表征。探讨了反应温度以及引发剂、乳化剂和VTMS浓度对乳液共聚合反应速率的影响。结果表明红外谱图中1096cm^-1处Si—O—Si键的吸收峰说明VTMS成功的与St、EA发生了共聚合反应；共聚物分子链中的硅氧烷水解产生的硅醇发生自缩合反应，从而使聚合物由线型结构变成交联的网状结构，因此提高了共聚物的热稳定性；升高反应温度、增大引发剂或乳化剂浓度以及降低VTMS浓度都可以提高聚合反应速率；得到了聚合反应活化能和动力学方程。

Synthesis and polymerization kinetics of styrene-ethyl acrylate-vinyltrimethoxysilane copolymers

Copolymers of styrene (St), ethyl acrylate (EA) and vinyltrimethoxylsilane (VTMS) have been synthesized by emulsion copolymerization using sodium dodecyl sulfate and polyoxyethylene octylphenol ether as emulsifiers in order to modify the thermal properties of the St-EA copolymers. The effects of varying the concentrations of emulsifier, initiator, and organosiloxane as well as the polymerization temperature on the polymerization conversion and rate were investigated in detail. The copolymer was characterized by infrared spectrometry (IR) and thermogravimetric analysis (TGA). Copolymerization of VTMS with St-EA was confirmed by the appearance of an absorption peak at 1096cm^-1 (due to Si—O—Si bonds) in the IR spectrum. The siloxane moieties in the copolymer chain underwent hydrolysis and self-condensation, resulting in a change in the structure of the copolymers from linear into a cross-linked network. As a result, the thermal stability of the copolymers was enhanced. The polymerization rate increased with increasing polymerization temperature, molar concentration of emulsifier and molar concentration of initiator and decreased with increasing molar concentration of VTMS. The apparent activation energy and kinetic features of the polymerization system were also obtained.