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通过活性正离子开环聚合的方法,以苯甲醇或月桂胺引发L-丙交酯聚合合成了一系列分子量可控的聚(L-乳酸)(PLLA).研究发现,端基刚、柔性的变化,改变了PLLA环带球晶的生成条件和环带周期结构,因此可以通过改变端基的结构来调控PLLA所形成的环带结构.分子量相近而端基不同的PLLA,在相同温度下结晶时,刚性引发剂苯甲醇引发的聚(L-乳酸)(B-PLLA)的球晶环带周期要远远小于具有柔性月桂胺端基的聚(L-乳酸)(L-PLLA),即刚性的端基对环带球晶生成的影响要大于柔性端基.具有相同端基的PLLA体系,聚合物在结晶区间内形成环带球晶的能力,随着分子量的增加而降低.
A series of poly (L-lactic acid) (PLLA) with controlled molecular weight were synthesized by the polymerization of L-lactide with benzyl alcohol or lauramine by the ring-opening polymerization of living positive ions. Changes the formation conditions of PLLA annulus spherulites and the periodic structure of the annulus so that the structure of the annulus formed by PLLA can be controlled by changing the structure of the end groups PLLA with similar molecular weight but different end groups crystallizes at the same temperature , The spherulitic zone cycle of the poly (L-lactic acid) (B-PLLA) initiated by the benzyl initiator of the rigid initiator is much less than that of the poly (L-lactic acid) The effect of rigid end groups on the formation of annular spherulites is greater than that of flexible end groups.In the PLLA system with the same end groups, the ability of the polymer to form ring-like spherulites in the crystallization zone decreases as the molecular weight increases.