Ionic Conductivity and Assembled Structures of Imidazolium Salt-Based Block Copolymers with Thermoresponsive Segments.

ABSTRACT: Ionic liquid-based block copolymers composed of ionic (solubility tunable)⁻nonionic (water-soluble and thermoresponsive) segments were synthesized to explore the relationship between ionic conductivity and assembled structures. Three block copolymers, comprising poly(N-vinylimidazolium bromide) (poly(NVI-Br)) as a hydrophilic poly(ionic liquid) segment and thermoresponsive poly(N-isopropylacrylamide) (poly(NIPAM)), having different compositions, were initially prepared by RAFT polymerization. The anion-exchange reaction of the poly(NVI-Br) in the block copolymers with lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂) proceeded selectively to afford amphiphilic block copolymers composed of hydrophobic poly(NVI-NTf₂) and hydrophilic poly(NIPAM). Resulting poly(NVI-NTf₂)-b-poly(NIPAM) exhibited ionic conductivities greater than 10-3 S/cm at 90 °C and 10-4 S/cm at 25 °C, which can be tuned by the comonomer composition and addition of a molten salt. Temperature-dependent ionic conductivity and assembled structures of these block copolymers were investigated, in terms of the comonomer composition, nature of counter anion and sample preparation procedure.

SUBMITTER: Nakabayashi K 

PROVIDER: S-EPMC6418687 | biostudies-other | 2017 Nov

REPOSITORIES: biostudies-other