Hydrogels with a memory: dual-responsive, organometallic poly(ionic liquid)s with hysteretic volume-phase transition

Kaihuan Zhang, Xueling Feng, Chongnan Ye, Mark A. Hempenius, Julius Vancso

Research output: Contribution to journalArticleAcademicpeer-review

26 Citations (Scopus)
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Abstract

We report on the synthesis and structure property relations of a novel, dual‐responsive organometallic poly(ionic liquid) (PIL), consisting of a poly(ferrocenylsilane) backbone of alternating redox‐active, silane bridged ferrocene units, and tetraalkylphosphonium sulfonate moieties in the side groups. This PIL is redox responsive due to the presence of ferrocene in the backbone, and also exhibits a lower critical solution temperature (LCST)‐type thermal responsive behaviour. The LCST phase transition originates from the interaction between water molecules and the ionic substituents and shows a concentration‐dependent, tunable transition temperature in aqueous solution. The PIL's LCSTtype transition temperature can also be influenced by varying the redox state of ferrocene in the polymer main chain. As the polymer can be readily cross‐linked and is easily converted into hydrogels, it represents a new dual‐responsive materials platform. Interestingly, the as‐formed hydrogels display an unusual, strongly hysteretic volume‐phase transition indicating useful thermal memory properties. By employing the dispersing abilities of this cationic PIL, CNT‐hydrogel composites were successfully prepared. These hybrid conductive composite hydrogels showed bi‐stable states and tunable resistance in heating‐cooling cycles.
Original languageEnglish
Pages (from-to)10029-10035
Number of pages9
JournalJournal of the American Chemical Society
Volume139
Issue number29
DOIs
Publication statusPublished - 26 Jul 2017

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