八甲基环四硅氧烷的转相乳液聚合  

PHASE INVERSION EMULSION POLYMERIZATION OF OCTAMETHYLCYCLOTETRASILOXANE

作　　者：黄学成 张建新 韩杰[1] 陈良恒[1] 

机构地区：[1]联合化学反应工程研究所华东化工学院分所

出　　处：《合成橡胶工业》1992年第3期142-145,共4页China Synthetic Rubber Industry

基　　金：上海市青年科学基金

摘　　要：以合成聚硅氧烷乳液为目的,对八甲基环四硅氧烷-十二烷基二甲基苄基溴化铵(D_4-QBr)体系的转相乳液聚合进行了研究。在反应温度60℃、反应时间24 h、初始水油比1∶1(质量比)、[QBr] 3.1％(质量)、[KOH]0.4％(质量)、搅拌速度500r/min的条件下,转相时体系的电导率为6×10^(-2)S/m,转相时间290 min,转相时单体转化率为36％。所得乳液的总固含量为50％(质量).该体系的转相方式为W/O—O/W/O—O/W。转相乳液聚合与常规乳液聚合相比。虽然两者的最终单体转化率、聚合物分子量及结构相同,但前者的聚合速率较高,乳液稳定(漂油量小于0.5％)。A new type of emulsion polymerization , phase inversion emulsion polymerization , was carried out by combining phase inversion with emulsion polymerization , and was used in preparing polysiloxan emulsion with total solid content 50% (mass).The exchanged liquid was prepared by mixing potassium hydroxide , dodecyldimethylbenzyl ammonium bromide and water at a desired ratio . The mixture was stirred and heated to 90°C , then kept this condition for 2 h . A measured amount of octamethylcyclotetrasiloxane ( D4) was placed in a tank . According to a given initial phase ratio of water to oil , exchanged liquid was added slowly to D4 while stirring . Then the system was heated to reaction temperature and kept for 8 -24 h .The system was tested with conductivity gauge , optical microscope and BI-90 particle sizer . The results show that the system is originally water in oil type emulsion (W/O) .phase inversion is induced by emulsion polymerization in the course of polymerization and the inversion way is W/O-O/W/O - O/W . Factors which are effective on phase inversion induced by emulsionpolymerization are reaction temperature , emulsifier concentration , initial phase ratio of water to oil and stirring speed .Catalyst concentration has influence on polymerization rate and phase inversion time , but it has no effect on conversion of D4 at phase inversion point .In normal emulsion polymerization ,a few of bigger monomer droplets and bigger polymer particles are the main factors which cause emulsion unstable . The effect of these two factors is weakened greatly in phase inversion emulsion polymerization , so stable emulsion with total solid content 50% can be prepared with oil separated less than 0.5% .The direction of mass transfer is changed by phase inversion , and it makes the polymerization macrokinetics changed . Phase inversion emulsion polymerization has higher polymerization rate but the final conversion of D4 is the same for that obtained in normal emulsion polymerization .

关 键 词：聚硅氧烷 乳液 乳液聚合 

分 类 号：O634.41[理学—高分子化学]