摘要
1937年Meerwein首次发现Et_3O^(+BF)可催化四氢呋喃(THF)开环聚合。到目前为止,发现能使THF开环聚合的催化剂有质子酸、Lewis酸、洋离子、正碳离子等。1990年吴健等将(Acac)_3Nd-(i-Bu)_3Al-H_2O-环氧氯丙烷催化体系应用于THF聚合,发现它和(i-Bu)_3Al-H_2O-环氧氯丙烷体系具有相同的活性,这说明稀土配合物没有参与活性中心的形成。本工作发现(CF_3CO-2)3Ln(Ln=Y,La,Ce,
Trifluoroacetates of rare earth (CF3CO2)aLn (Ln = Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,and Tm) combined with alkyl aluminium RnAlH3-n(R= methyl,octyl,n=3; R = ethyl,iso-butyl,n=3,2) were first used as catalysts for the ring opening polymerization of tetra-hydrofuran (THF).The activity was greatly increased by adding promoter (PE) to the catalyst system,and was decreased by adding a little amount of water.It was found that this catalyst system was favorable for the polymerization of THF with.high,activity,and high molecular weight polytetrahydrofuran could be obtained.The effects of Ln,Al/Ln,PE/Ln,RnAlHs-,,and temperature etc.on the polymerization activity were also studied.
关键词
稀土催化剂
四氢呋喃
开环聚合
Rare earth catalyst
tetrahydrofuran
ring opening polymerization
