双金属催化环氧化物聚合动力学研究

研究了双金属氰化络合催化剂DMC催化环氧丙烷聚合的动力学 .用测定反应过程体系压力变化来决定聚合的起始速率 ,发现聚合反应速率正比于催化剂用量C ,单体浓度M的平方 .该实验规律可以从单体参与链引发的动力学特点解释 .考察了温度对聚合反应速率的影响并求得了表观活化能为 5 9 1kJ·mol- 1 ,该值与环氧聚合的卟啉铝、稀土络合物等催化体系接近 .

KINETICS OF DOUBLE METAL CYANIDE COMPLEX CATALYZED PROPYLENE OXIDE POLYMERIZATION

The kinetics of polymerization of propylene oxide(PO) catalyzed by zinc hexacyanocobaltate complex catalyst was studied by means of pressure measurements. All the reactions were carried out in 0.1 L autoclaves equipped with manometers.As soon as the pressure of the system began to decrease,the polymerization was considered to have been initiated.By evaluation of vapor - liquid equilibrium of toluene solutions of propylene oxide,the pressure was found to linearly depend on the PO volume fraction. Therefore,the rate of the reaction was known to be proportional to the rate of pressure decreasing. The influence of reaction temperature,catalyst and monomer concentrations on the reaction rate was investigated. It was found that the polymerization was a first order reaction to the concentration of catalyst C,but a second order reaction to that of monomer M as shown in the following equation. The rates also depended on reaction temperature while the apparent activation energy was 59 1?kJ/mol according to the Arrhenius equation. It was proposed that the epoxide monomer must be involved in the initiation stage of the polymerization. Based on this assumption a kinetic equation in which K was a rate constant was deduced in well accordance with the experimental results:R P=KM2C.