Ishikawa Aoto, Ouchi Makoto
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
ACS Macro Lett. 2024 Aug 20;13(8):1072-1078. doi: 10.1021/acsmacrolett.4c00290. Epub 2024 Aug 2.
Alternating graft copolymers were precisely synthesized via selective cyclopolymerization of pendant-transformable divinyl monomer (), post-polymerization modification via aminolysis with alkylamine, and ring-opening polymerization of l-lactide (LLA) from the hydroxy pendant group in alternating sequence. The poly(LLA) (PLLA) graft chain on the alternating copolymer gave a higher crystallization degree on the isothermal treatment than that on the random counterpart likely because of the periodic sequence. The comonomer pendant group from alkylamine in the aminolysis reaction in the alternating sequence affected the crystallization behaviors, and the oligoethylene glycol (OEG) group promoted the crystallization thanks to the larger free volume effect. As for the stereocomplex formation of the racemic mixture of enantiomeric PLLA and poly(d-lactide) (PDLA) chains, the alternating graft copolymer gave a higher degree of stereocomplex crystallization in the mixture with the enantiomer homopolymer than the random analogue.
通过侧基可转化二乙烯基单体的选择性环化聚合、用烷基胺进行氨解的后聚合改性以及从羟基侧基以交替顺序进行的丙交酯（LLA）的开环聚合，精确合成了交替接枝共聚物。交替共聚物上的聚（LLA）（PLLA）接枝链在等温处理时比无规对应物具有更高的结晶度，这可能是由于周期性序列的缘故。交替序列中氨解反应中来自烷基胺的共聚单体侧基影响结晶行为，并且聚乙二醇（OEG）基团由于较大的自由体积效应而促进了结晶。至于对映体PLLA和聚（d-丙交酯）（PDLA）链的外消旋混合物的立体复合形成，交替接枝共聚物在与对映体均聚物的混合物中比无规类似物具有更高程度的立体复合结晶。
