Semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion

被引：12

作者：

Mohoric, Ines ^{[2
]}

Sebenik, Urska ^{[1
]}

机构：

[1] Univ Ljubljana, Fac Chem & Chem Technol, Ljubljana 1000, Slovenia

[2] Hidria Inst Mat & Technol, Sp Idrija 5281, Slovenia

来源：

POLYMER | 2011年 / 52卷 / 20期

关键词：

Polysiloxanes; Emulsion polymerization; Anionic polymerization; Semibatch process; CATIONIC-POLYMERIZATION; AQUEOUS EMULSION; MECHANISM;

D O I：

10.1016/j.polymer.2011.07.045

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

The semibatch anionic ring-opening polymerization of octamethylcyclotetrasiloxane in emulsion was studied under the condition of no seed particles used in polymerization system. Concentration of emulsifier was set above critical micelle concentration. Effect of monomer feed rate on the chemical kinetics, average particle size and distribution and on the polymer molar mass and distribution was investigated. During monomer addition, polymerization rate was constant and controlled by the monomer feed rate. According to the proposed mechanism for anionic polymerization in emulsion, it was assumed that also the number of active polymerization sites and monomer concentration at the particle surface, where propagation occurs, remain constant. A continuous increase of average particle size and absence of extensive condensation reactions at high conversion suggested that the freshly added monomer diffuses toward hydrophobic polymer particles, where it is consumed in propagation reaction and/or accumulated in the particle core. (C) 2011 Elsevier Ltd. All rights reserved.

引用

页码：4423 / 4428

页数：6

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