Effect of oligooxyethylene side chains on lyotropic liquid crystallinity and proton conduction of sulfonated polyimide thin films

Abstract

In this study, we newly synthesized a sulfonated polyimide with oligooxyethylene side chains (APOS-PMDA). The oligooxyethylene groups increased the hydrophilicity of the side chains compared to the reported ASPI-2 with alkyl chains, therefore results in more water adsorption at high humidity range. Under humidified conditions, the newly synthesized polymer thin film exhibited lamellar structure driven by lyotropic liquid crystalline property. The APOS-PMDA thin film showed a proton conductivity of 0.11 S / cm at 95% RH and room temperature. These results provide a new perspective for exploring the influence of side chain properties on lyotropic liquid crystalline property.