Laboratory of Polymer Chemistry, Graduate School of Bioagricultural Sciences, E1-1(300), Nagoya University, Nagoya 464-8601, Japan.
J Am Chem Soc. 2010 Feb 17;132(6):1750-1. doi: 10.1021/ja9089395.
The bulky substituents of homosalen complexes decelerate the ring-opening polymerization of racemic lactide (LA). The substituent effects provide the first catalysis for the random copolymerization of epsilon-caprolactone (CL) with LA (CL/LA = 1:1). The copolymerization of CL with LA (CL/LA = 1:1) by the iPr(3)Si-substituted homosalen-Al complex 2 affords the practically random copolymer in a controlled manner. The reactivity ratios, average sequence lengths of CL and LA during the copolymerization, abundance ratios of the triad caproyl sequences, and T(g) value of the obtained copolymer indicate that the copolymer was random with a somewhat alternative tendency (r(CL)r(LA) = 0.80).
偕胺肟配合物的庞大取代基会降低消旋丙交酯（LA）的开环聚合速度。取代基效应为 ε-己内酯（CL）与 LA（CL/LA=1:1）的随机共聚提供了首例催化。用异丙基取代的偕胺肟-铝配合物 2 引发 CL 与 LA（CL/LA=1:1）共聚，以可控方式得到近乎无规的共聚物。共聚过程中的竞聚率、CL 和 LA 的平均序列长度、己酰基三单元组的丰度比以及所得共聚物的玻璃化转变温度（Tg）表明，该共聚物具有一定的交替倾向（r（CL）r（LA）=0.80），属于无规共聚物。
