Effect of composition and stereoregularity on phase-transition behavior of aqueous N-ethylacrylamide/N-n-propylacrylamide copolymer solutions

Tomohiro Hirano, Akiko Ono, Hiroaki Yamamoto, Takeshi Mori, Yasushi Maeda, Miyuki Oshimura, Koichi Ute

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Radical copolymerizations of N-ethylacrylamide and N-n-propylacrylamide (NNPAAm) at various ratios were carried out at -40 C, in toluene in the presence of 3-methyl-3-pentanol, or in N-ethylacetamide. Syndiotactic-rich copolymers with racemo diad contents of 67.1-70.2%, and isotactic-rich copolymers with meso diad contents of 60.9-64.5% were prepared. Syndiotactic-rich copolymers with NNPAAm compositions of ≥92.9 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Isotactic-rich copolymers with NNPAAm compositions of 39.2-67.6 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Those of composition >67.6 mol% were insoluble in water. Stereosequence analysis suggested that isotactic sequences favored intramolecular hydrogen bonding between contiguous NNPAAm units, more than syndiotactic sequences. Enhanced intramolecular hydrogen bonding in isotactic sequences was responsible for the large hystereses and insolubility of isotactic-rich copolymers with high NNPAAm compositions.

Original languageEnglish
Pages (from-to)5601-5608
Number of pages8
Journalpolymer
Volume54
Issue number21
DOIs
Publication statusPublished - Oct 4 2013

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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