Ion-Containing Polymer-Grafted Nanoparticles in Ionic Liquids: Implications for Polymer Electrolyte Membranes
Siqi Liu, Di Wu, Pinar Akcora
Abstract
Polymer-grafted nanoparticles offer several advantages in designing electrolyte systems for their uses in fuel cells, supercapacitors, or actuators. In this work, stabilization of poly(methyl methacrylate) (PMMA)-grafted magnetic nanoparticles with polystyrene sulfonate (PSS) end domains in ionic liquid/cosolvent mixtures is presented. We propose that anions and cations pertaining to ionic liquid preferentially interact with the methyl groups of PMMA and the sulfonated groups of PSS, respectively. These interactions can be used to mitigate the whole ionic conductivity and the free mobile counterion distribution in the copolymer-grafted nanoparticle-based electrolyte membranes. PMMA-b-PSS-grafted nanoparticles with low sulfonation amount and long PMMA chains are found to exhibit the highest conductivity in acetonitrile and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIM-TFSI) mixtures compared to the particles with the higher sulfonation amount and shorter PMMA chains.