三(4-异丙基芳氧基)稀土催化ε-己内酯开环聚合

Ring-opening polymerization of ε-caprolactone catalyzed by rare earth tris(4-isopropylphenolate)s

合成了三(4-异丙基芳氧基)稀土[Ln(OPIP)3],并用于催化ε-己内酯开环聚合。研究结果表明,在不同稀土元素的化合物中,三(4-异丙基芳氧基)镧[La(OPIP)3]具有较高的催化活性,在非极性溶剂中,ε-己内酯的转化率和聚己内酯的分子量较高。La(OPIP)3催化ε-己内酯聚合的适宜条件为:ε-已内酯浓度为2.5 mol·L-1,n(ε-己内酯):n(La)=1 000,60℃,60 min,甲苯作溶剂。在此条件下,聚己内酯的数均分子量为11.40×104,分子量分布为1.31。利用1HNMR分析聚合物端基表明,该反应按"配位-插入"机理进行。

Rare earth tris（4-isopropylphenolate）s [ Ln （OPIP）3 ] was synthesized and used as the catalyst for ring-opening polymerization of e-caprolactone. The results indicated that rare earth tris （4-iso- propylphenolate）s doped with lanthanum [La（ OPIP）3 ] exhibited higher activity in non-polar solvents, with higher monomer conversion and higher molecular weight of palycaprolactone. The optimum condition for ring-opening polymerization of e-caprolactone over lanthanum tris（4-isopropylphenolate）s was as follows ： e-caprolactone concentration 2.5 mol · L - 1, n （e-caprolactone） ： n （La） = 1 000,60 ℃, 60 rain, toluene as the solvent. Number-average molecular weight of 11.40 × 104 and molecular weight distribution of 1.31 for polycaprolactone was obtained under the optimum condition. 1 HNMR analysis indicated that mechanism for the polymerization over lanthanum tris （4-isopropylphenolate） followed a monomer inserting into the growing chains and acyl-oxygen bond scission path.