Design of maleimide monomer for higher level of alternating sequence in radical copolymerization with styrene. Issue 3 (9th September 2018)

• Record Type: Journal Article
• Authors: Nishimori, Kana; Sawamoto, Mitsuo; Ouchi, Makoto
• Is Part Of: Journal of polymer science. Volume 57:Issue 3(2019)
• Page Start: 367
• Page End: 375
• Publication Date: 2018-09-09
• Subjects: alternating copolymerization -- living polymerization -- radical polymerization -- sequence -- styrene; 547
• DOI: 10.1002/pola.29191
• Languages: English
• ISSNs: 0887-624X

Abstract

ABSTRACT: This work deals with design of maleimide monomer toward more precise control of alternating sequence for radical copolymerization with styrene. Crucial in this study is sequence analysis by MALDI‐TOF‐MS for resultant copolymers that was obtained via ruthenium‐catalyzed living radical copolymerization with a malonate‐based alkyl halide initiator showing selective initiation ability. The copolymers of a simple N ‐alkyl maleimide [e.g., N ‐ethyl maleimide (EMI)] with styrene gave complicated peak patterns for the MALDI‐TOF‐MS spectra indicating low degree of alternating sequence, in contrary to expectation from the reactivity ratios (almost zero). A simple substitution of methyl group (CH3 ) of EMI with trifluoromethyl (CF3 : CF3 ‐MI) made the peak patterns much simpler giving the copolymer with higher alternating sequence. More interestingly, the peak interval of the copolymer at earlier polymerization stage was equal to sum of the molecular weights of CF3 ‐MI and styrene, suggesting possibility of the pair propagation of the monomers. Indeed, 1 H NMR analyses of the mixture of maleimide with styrene suggested stronger interaction of CF3 ‐MI than EMI. Based on the results, maleimide derivatives carrying a substituent‐designable electron‐withdrawing group [ROC(O)N–: R = substituent] were newly designed toward incorporation of functional side chains. They also gave higher alternating sequence for the copolymerization with styrene. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019, 57, 367–375 Abstract : Sequence analysis by MALDI‐TOF‐MS revealed the copolymers of a simple N ‐alkyl maleimide [e.g., N ‐ethyl maleimide (EMI)] with styrene have a low degree of alternating sequence, in contrast to the expectation from the reactivity ratio (almost zero). Design of more electron‐deficient maleimides [ N ‐(2, 2, 2‐trifluoroethyl) maleimide, N ‐alkoxycarbonyl maleimides] made MALDI‐TOF‐MS spectra simpler and dramatically improved the accuracy of the alternating sequence due to the stronger interaction with styrene.