八甲基环四硅氧烷阳离子开环乳液聚合研究

Study of cationic ring-opening emulsion polymerization of octamethylcyclotetrasiloxane

以十八烷基三甲基氯化铵(OTAC)和异构十三醇聚氧乙烯醚(1307)为复合乳化剂,KOH为催化剂,八甲基环四硅氧烷(D4)为单体,制备了聚硅氧烷乳液。比较了高压均质、超声波处理和高速剪切3种乳化方式对乳液透光率、电导率、黏度以及贮存稳定天数的影响,考察了复合乳化剂配比及用量、KOH用量和反应温度对乳液稳定性和聚合动力学的影响。结果表明,采用30 MPa高压均质后的乳液稳定性最好。m(OTCA)∶m(1307)=1∶1时,乳液稳定性较好,且随着复合乳化剂用量的增加,乳液凝胶率降低,乳液稳定性提高。当m(OTCA)∶m(1307)=1∶1时,OTAC的表观反应级数为0.16;当复合乳化剂质量分数为3%时,OTCA的表观反应级数为0.21;KOH的表观反应级数为0.57,表观活化能为42.66 kJ.mol-1。

Polysiloxane emulsions were prepared by using octamethylcyclotetrasiloxane as monomer, blended surfactant composed of octadecyltrimethylammonium chloride （OTAC） and ethoxylated iso - tridecanol （ 1307 ） as emulsifier and KOH as catalyst. Three emulsification methods：high pressure homogenizer, ultrasonic treatment and high speed shearing were carried out to compare the result in aspect of light transmittance, electric conductance, viscosity and storage stability of the emulsion. Effects of mass ratio of the surfactant constituents in the emulsifying agent, dosage of blend emulsifying agent, dosage of KOH catalyst, as well as the reaction temperature on stability of the emulsion and polymerization kinetics were investigated. Results showed that using 30 MPa high pressure homogenizer will result - in best emulsion stability as compared with other methods. When m（OTCA） ： m（ 1307 ） = 1： 1, the emulsion stability is rather good. Following the increase of emulsifying agent dosage, the fraction of gel content in the emulsion is reduced, and the stability of the emulsion is upgraded. Under the condition as m （OTCA） ： m （ 1307 ） = 1 ： 1, the apparent reaction order is 0. 16. When the mass ratio of the blend emulsifier is 3% ,the apparent reaction order is 0.21. The apparent reaction order of KOH catalyst is 0. 57, and its apparent activation energy is 42. 66 kJ· mol^ - 1.