Kametani Yuki, Sawamoto Mitsuo, Ouchi Makoto
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan.
Institute of Science and Technology Research, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi, 487-8501, Japan.
Angew Chem Int Ed Engl. 2018 Aug 20;57(34):10905-10909. doi: 10.1002/anie.201805049. Epub 2018 Jul 23.
An alternating copolymer of methacrylic acid and N-isopropyl acrylamide (NIPAM) was synthesized by selective cyclopolymerization of a special divinyl monomer and transformation of repeating cyclo-units in the resultant cyclopolymer. Crucial to the breakthrough is the monomer design in view of two types of cleavable bonds (3° ester and activated ester) in the pendant group of the monomer and the lower reactivity ratio of the two double bonds (methacrylate and electron-poor acrylate) for the polymerizable groups. The thus-obtained cyclopolymer was transformed into the alternating copolymer by transformation of the activated ester into amide by isopropyl amine and cleavage of the 3° ester by trifluoroacetic acid. The resultant copolymer showed thermal and pH response in aqueous solution that was different from the 1:1 random copolymer as well as the homopolymers.
通过特殊二乙烯基单体的选择性环化聚合以及所得环化聚合物中重复环单元的转化，合成了甲基丙烯酸与N-异丙基丙烯酰胺（NIPAM）的交替共聚物。鉴于单体侧基中的两种可裂解键（叔酯和活化酯）以及可聚合基团的两个双键（甲基丙烯酸酯和贫电子丙烯酸酯）的较低竞聚率，单体设计对这一突破至关重要。通过用异丙胺将活化酯转化为酰胺以及用三氟乙酸裂解叔酯，将由此获得的环化聚合物转化为交替共聚物。所得共聚物在水溶液中表现出与1:1无规共聚物以及均聚物不同的热响应和pH响应。
