Unusual Radical Copolymerization of Suprabulky Methacrylate with N-Hydroxysuccinmide Acrylate: Facile Syntheses of Alternating-Rich Copolymers of Methacrylic Acid and N-Alkyl Acrylamide

In this work, we provide a facile methodology to synthesize AB alternating-rich copolymers made of methacrylic acid (MAA) and alkyl acrylamide units. An extremely bulky tent-alkyl methacrylate carrying ethyl and fenchol substituents (EFMA) was newly designed as a special monomer that is inactive for homopolymerization but active for copolymerization in radical polymerization. Indeed, EFMA showed a unique radical copolymerization behavior to the bulkiness, which was quite different from a general methacrylate (i.e., methyl methacrylate). The copolymerization of EFMA with an electron-deficient acrylate carrying a N-hydroxysuccinimide substituent followed by postreactions (i.e., acidolysis and aminolysis) for both units afforded an alternating-rich copolymer of MAA and alkyl acrylamide units. The sequence was characterized by C-13 NMR analyses in comparison with the statistical copolymers and homopolymers. The reactivity ratio values also supported the process of alternating copolymerization. The thus-obtained alternating-rich copolymers of MAA with isopropyl acrylamide or octadecyl acrylamide showed sequence-driven solubilities and thermal response properties.