Facile Fabrication Technique of Polymeric Ionic Liquids-Coated Core-Shell Nanoparticles for Polymer Electrolyte Membranes

Nanoparticles and nanofibers are widely used as components of polymer electrolytes for membranes in fuel cells, and many surface modification methods are reported. However, some fabrication techniques are complicated, and it is necessary to develop a simplified and precise control method. Herein, a facile fabrication method is reported for core-shell nanoparticles hierarchically coated with polymeric ionic liquids (PIL) and hydrophobic polymers as a material for polymer electrolytes. A hierarchical polymer layer on the surface of the SiO2 nanoparticles is easily constructed by repeating the facile polymer-coating technique based on precipitation polymerization several times. The highest proton conductivity of the core-shell nanoparticles is 1.3 x 10-2 S cm-1 at 80 degrees C and 95% relative humidity. Although the hydrophobic polymers coated as a protective layer reduce the proton conductivity, the formation of the PIL enhances the proton conductivity in various temperature and humidity environments. Therefore, the proposed method enables the facile fabrication of polymer layers with multiple functions, such as a proton-conductive PIL layer and hydrophobic polymer layers as protective layers on the surface of the nanoparticles. Furthermore, they are expected to be applied to energy supply and gas separation, including polyelectrolytes, for the realization of a sustainable society. Proton-conductive core-shell nanoparticles with hierarchical polymer layers as shells are prepared by an in-situ polymerization method, and shells contain polymeric ionic liquids. The core-shell nanoparticles exhibit proton conductivity in both high- and low-humidity conditions. This method is expected to be applicable not only to the fabrication of proton-conductive nanoparticles but also to the fabrication of various functionalized nanoparticles.image