【摘要】 以四甲基氢氧化铵为引发剂 ,八甲基环四硅氧烷为单体 ,水为封端剂 ,在改进的工艺条件下 ,一步制得羟基聚硅氧烷 .并采用凝胶色谱 (GPC)研究上述一步合成法的动力学 .在经典的环硅氧烷阴离子开环聚合理论基础上 ,结合水对反应的影响 ,提出一步合成法的反应机理并推导了反应动力学模型 .同时应用该模型定量计算出活性中心浓度 ,发现活性中心浓度随反应分迟滞期、增长期、恒定期 3个阶段 .而不同反应阶段活性中心络合结构的红外光谱 (FT IR)检测证实了上述结论 .更多还原

【Abstract】 Hydroxy terminated polydimethylsiloxane (PDMS) is one of the important silicone products. In this paper, PDMS was synthesized in one-step process with cyclosiloxanes as monomer and a base as initiator when the reaction was under the conditions of high temperature, adding water and oxygen-off. The kinetics of the reaction was studied by Gel Permeation Chromatography (GPC). Furthermore, from the reaction conditions of one-step process, the chemical features of such one-step process could be expressed as anionic ring-opening polymerization of cyclosiloxanes under the influence of water. So based on the classical mechanism study on anionic ring-opening polymerization of cyclosiloxanes,the reaction mechanism of such one-step process was proposed, the kinetic model of the one-step process was derived. The change of the concentration of active centers with the progress of reaction was quantitatively obtained according to the kinetic model. There are three periods:sluggish period, increasing period, and constant period. The results described above were also verified by examining the complex structure of the reaction mixture with infrared spectroscopy (IR).更多还原