High-Fidelity Hydrogel Thin Films Processed from Deep Eutectic Solvents

David E. Delgado, Daniel R. King, Kunpeng Cui, Jian Ping Gong, Kenneth R. Shull

Research output: Contribution to journalArticlepeer-review

Abstract

Polyampholyte (PA) hydrogels are a fascinating class of soft materials that can exhibit high toughness while retaining self-healing characteristics. This behavior results from the random distribution of oppositely charged monomers along the polymer chains that form transient bonds with a range of bond strengths. PAs can be dissolved in aqueous salt solutions and then recast via immersion precipitation, making them particularly useful as surface coatings in biomedical applications. Moreover, this immersion precipitation technique allows these PA hydrogels to be fabricated into films less than 100 nm. One critical challenge to this aqueous processing method is the recrystallization of the salt upon water evaporation. Such recrystallization can disrupt the hydrogel morphology especially in thin films. In this study, a deep eutectic solvent (DES) formed from urea and choline chloride was used to dissolve PAs made from p-styrenesulfonic acid sodium salt and 3-(methacryloylamino)propyl trimethylammonium chloride. This DES has a freezing point of 12 °C, allowing it to remain stable and liquid-like at room temperatures. Thus, these PAs can be processed in DES solutions, without this issue of recrystallization and with simple methods such as spin coating and dip coating. These methods allow these hydrogels to be used in thin (<100 nm)-film coating applications. Finally, the complete miscibility of DES in water allows a wider range of one-phase compositions and expands the processing window of these polyampholyte materials.

Original languageEnglish (US)
Pages (from-to)43191-43200
Number of pages10
JournalACS Applied Materials and Interfaces
Volume12
Issue number38
DOIs
StatePublished - Sep 23 2020

Keywords

  • deep eutectic solvents
  • ionic liquids
  • polyampholytes
  • polyelectrolyte complexes

ASJC Scopus subject areas

  • Materials Science(all)

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