Synthesis of Polymers Having N-Hydroxymaleimide Units by Thermolysis of N-(Isopropyloxycarbonyloxy)maleimide Polymers

摘要

N-(Isopropyloxycarbonyloxy)maleimide (iPOCMI) has been synthesized and polymerized to give both the homopolymer and copolymers with substituted styrenes. These polymers were readily deprotected by thermolysis of the isopropyloxycarbonyl (iPOC) groups to provide the corresponding N-hydroxymaleimide (HOMI) polymers. The homopolymer and styrenic copolymers of iPOCMI were radically obtained in higher conversion and higher molecular weight than those obtained by direct polymerizations of N-hydroxymaleimide. The homopolymer of iPOCMI was transformed into poly(N-hydroxymaleimide)P(HOMI) by thermolysis of iPOC groups at 205 ∩ with concurrent release of propene and carbon dioxide. The copolymer of iPOCMI and styrene was thermally deprotected to the copolymer of HOMI and styrene at 235 ∩. The mass loss was 28% and the Tg of the resulting copolymer was 250 ∩. The thermal deprotection readily provided the desired, polar HOMI polymers which have Tgs above 240 ∩. The deprotection was accompanied by large changes in aqueous base solubility.