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 ([EMI][TFSA]). Simultaneous polymerization and crosslinking of phenol with paraformaldehyde in [EMI][TFSA] 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 [EMI][TFSA] 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 × 10−3 S cm−1 at 30 °C), which is comparable to the pristine ionic liquid [EMI][TFSA]. We report transparent ion conductive ionic liquid-phenol resin hybrids prepared by in situ polymerization/crosslinking of phenol monomer in ionic liquid. The transparent hybrid prepared from 20 wt% monomer concentration exhibited high thermal stability and ionic conductivity (1.0 × 10−3 S cm−1 at 30 °C), which is comparable to the pristine ionic liquid.