调节剂存在下双金属氰化络合催化剂催化环氧丙烷聚合的动力学

KINETICS OF DMC CATALYZED POLYMERIZATION OF PROPYLENE OXIDE IN THE PRESENCE OF REGULATORS

研究了双金属氰化络合催化剂DMC催化环氧丙烷调节聚合的动力学 .通过测定反应过程体系压力的变化来决定聚合的起始速率 ,发现聚合反应速率与分子量调节剂浓度Tr的线性函数的 - 1次方成正比 .考察了DMC催化剂在反应不同阶段的远红外吸收变化 ,提出了聚合反应可能的反应历程 ,并推导出调节聚合的动力学方程 .研究结果表明调节聚合的动力学特点在于链引发是发生在催化剂与单体之间 。

In a previous paper,the rate of propylene oxide (PO) polymerization catalyzed by double metal cyanide complexes (DMC) had been determined to be pro portional to the catalyst amount c and the square of monomer concentration M.The same reaction in the presence of substances containing ac tive hydrogens which were applied to regulate the molecular weights of the produ ced polyethers was inrestigated in this paper.All the reactions were carried out in 0 1 L autoclaves equipped w ith manometers and the induction period t 0 and polymerization rate R p were det ermined by means of pressure measurements.It was found that regulators with high er OH functionality showed greater influence on t 0,which was prolonged wit h ad dition of regulators except cyclohexanol.It was also found that the polymerizat ion rate depended on the type of regulators and was inversely proportional to a linear function of the regulator concentration Tr.Moreover, a limited amount of water behaved as a strong bifunctional regulator which intensively influenced t 0 an d R p; the presence of excess water deactivated the catalyst and hindered t he polymerization.It w as revealed that the DMC catalyst and the monomer both were necessary for the in i tiation of the polymerization.Based on this understanding,a possible mechanism w as propo sed for the polymerization and a kinetic equation as following was deduced,which was in well accordance with experimental results.R\-p=KM 2c/(1+kTr)