Fe-Zn双金属氰化物催化环氧丙烷开环聚合的研究

用Fe Zn双金属氰化物 (DMC)催化剂合成了数均分子量 30 0 0～ 12 0 0 0的聚氧化丙烯二元醇 .着重考察了聚合反应的温度、加料方式等对聚合物分子量及分布的影响 ,并初步探讨了Fe Zn双金属氰化物催化环氧丙烷开环聚合的反应特征 .实验发现 ,采用Fe ZnDMC催化剂 ,聚合物分子量可控 ;在较高温度下聚合所得的聚合物分子量分布呈双峰形 ,显示反应体系中至少存在两类活性中心 ,这可能与催化剂中存在两种价态的络合物有关 ,当降低聚合温度时 ,聚合物分子量分布呈单峰形 ,可能是一类活性中心没有引发 ;实验中还发现单体分批加料时聚合物分子量分布较窄 ,而一步加料法所得聚合物分子量分布则很宽

RING-OPENING POLYMERIZATION OF PROPYLENE OXIDE INITIATED BY Fe-Zn DOUBLE METAL CYANIDE CATALYST

Fe-Zn double metal cyanide (DMC) complexes are relatively cheap and effective catalysts for the ring-opening polymerization of propylene oxide. Polyoxypropylene diol oligomer is used as the initiator. Polyoxypropylene diols having Mn within the range of about 3000 to 12000 are prepared with Fe-Zn DMC catalyst under mild condition. The polymer is characterized by GPC and VPO. Effect of polymerization condition on molecular weight(MW) and molecular weight distribution(MWD) is investigated. The MW of polymer may be controlled by monomer/initiator molar ratio(M/I). It is assumed that each activated catalyst site is related with many different molecules during polymerization. Polymerization proceeded at 80℃ and 60℃ gives polymers with a bimodal MWD(at least two kinds of active centers) and a unimodal MWD, respectively. When polymerization proceeds at temperatures lower than 65℃, the active center associated with Fe(CN)64- may not act because of its low activity. Two types of anion Fe(CN)63- and Fe(CN)64- coexisting in Fe-Zn DMC catalysts, which possibly result in the bimodal MWD, have been proved by IR spectra and X-ray diffraction.