环氧化物稀土络合催化开环聚合动力学研究

用膨胀计方法研究环氧丙烷、环氧氯丙烷在稀土络合催化剂 Nd(P_(204))_3-Al(i-Bu)_3-H_2O作用下的聚合反应动力学,表明聚合反应速度对催化剂浓度及单体浓度均呈一级关系。环氧丙烷、环氧氯丙烷开环聚合反应活化能分别为61.3kJ/mol和48.9kJ/mol。在同样的聚合反应条件下,环氧氯丙烷聚合反应速度大于环氧丙烷聚合反应速度。 研究还发现,催化剂组成摩尔比Al/Nd及H_2O/Al对聚合反应速度均有一定影响;各种稀土元素络合催化剂催化活性顺序为:Nd>La>Dy>Yb>Eu;稀土络合物中配体对活性的影响为:acac>P_(204)>P_(507)>naph;烷基铝的影响为:Al(i-Bu)_3>AlEt_3。

A KINETIC STUDY OF RING-OPENING POLYMERIZATION OF ALKYLENE OXIDE BASED ON RARE EARTH COORDINATION CATALYSTS

The kinetics of polymerization of PO and ECH using rare earth coordination catalyst composed of Neodynium 2-Ethylhexyl Phosphonatestriisobutyl Aluminum-water in toluene have been studied by a dilatometer method. It has been shown that the rate of polymerization is first order with respect to both monomer and catalyst concentrations. According to Arrhenius equation, it was found that polymerization activstion energies for PO and ECH are 61.3 Kj/mol and 48.9 Kj/mol respectively. Under the same conditions, propylene oxide polymerization proceeded fasfer than ECH polymerization.Al/Nd molar ratio and H2O/A1 molar ratio also have some effects on the polymerization rate, and the same is catalyst composition. The activity sequence for different rare earth element catalyst systems decresses in the following order: Nd>La>Dy>Yb>Eu; activity sequence of catalysts containing different ligands decreases in the order: acac>P204>P507> naph; and the activity of Al(i-Bu)s system is higher than that of catalyst with AlEt3.