锌配合物催化ε-己内酯/L-丙交酯共聚制备环状和线形嵌段共聚酯

Synthesis of Cyclic and Linear Block Copolyesters via Ring-opening Copolymerization of ε-Caprolatone and L-Lactide Catalyzed by Zinc Complex

以空气稳定的含苯并咪唑基吡啶醇配体的氯化锌配合物为催化剂,与甲基锂相结合,在有无苄醇引发的情况下,分别研究了L-丙交酯(L-LA)的均聚反应以及L-丙交酯和ε-己内酯(ε-CL)的共聚反应.L-丙交酯的均聚反应与ε-己内酯的均聚反应相似,具有较高的聚合活性;聚合物的结构分析结果表明,在聚合体系中有无苄醇存在的情况下,分别得到以线形和环状聚丙交酯(PLA)为主的聚合产物;而加入苄醇后聚合物的分子量降低,分子量分布变窄.在L-丙交酯和ε-己内酯均聚反应的基础上,对2种单体的共聚反应进行了研究.通过顺序加料法,调节ε-CL/L-LA的起始投料比,在有无苄醇存在下,分别制备了一系列不同ε-CL/L-LA比例的线形和环状嵌段共聚物,对均聚物和共聚物的结构和热性能进行了表征.

In combination with methyllithium,ring-opening polymerization（ROP） of L-lactide（L-LA） and copolymerization of ε-caprolactone（ε-CL） and L-LA were investigated in the presence or absence of benzyl alcohol by using an air-stable zinc complex bearing（benzimidazolyl） pyridine alcohol ligand. Similar to the polymerization of ε-CL,the monomers were completely converted to polymers in short time in all the cases and high catalytic activities were achieved in the ROP of L-LA. The structural analysis of polymers indicated that in the absence of benzyl alcohol,the polymers obtained were mainly cyclic PLA with relatively broad molecular weight distribution, whereas linear PLA with lower molecular weight and narrower molecular weight distribution predominated in the presence of benzyl alcohol. On the basis of ROP of ε-CL and L-LA,the ring-opening copolymerization of ε-CL and L-LA was studied with the different CL/LA feeding ratios. A series of linear and cyclic block copolymers with different CL/LA molar ratios was synthesized by the sequential feeding strategy according to the presence or absence of benzyl alcohol in the reaction system. The structure and thermal properties of homopolymers and copolymers were characterized by FTIR,1 H NMR,13 C NMR,GPC,DSC and TGA analysis.