Transparent ionic liquid-phenol resin hybrids with high ionic conductivity

Abstract

We report transparent ion conductive ionic liquid-phenol resin hybrids prepared by in situ polymerization/crosslinking of phenol monomer in ionic liquid. As ionic liquid, we used highly ion conductive ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (EMITFSA). Simultaneous polymerization and crosslinking of phenol with paraformaldehyde in EMITFSA yielded a highly transparent film. From a field emission scanning electron microscope (FE-SEM) image at 5000 magnification, the transparent hybrid prepared by in situ method did not show phase separation at 5000 magnification. In addition, from the FE-SEM image of the transparent hybrid at high magnification (× 60 000), phenol resin and EMITFSA were observed to be integrated at a scale of a few nanometers. The transparent hybrid containing 20 wt% phenol resin showed high thermal stability and ionic conductivity (1.0 × 103 S cm-1 at 30 °C), which is comparable to the pristine ionic liquid EMITFSA. © The Society of Polymer Science, Japan (SPSJ) All rights reserved.