Atomistic Insights into Structure–Morphology Relationships in Hydrated Poly(benzimidazolium) and Poly(bis-arylimidazolium) Ionene Membranes

Abstract

Ease in preparation and the alkaline stability characteristics spurred immense interest in polyelectrolytes composed of poly(benzimidazolium) (HMT-PMBI) and poly(bis-arylimidazolium) (PAImMM) Ionene anion exchange membranes. The present work emphasises the structure and morphological traits of hydrated structures based on ionene membranes using molecular dynamics simulations. The influence of benzimidazolium group and bis-arylimidazolium group on hydrated structure of membrane is analysed through Radial distribution function and structure factor at 300 and 333 K. A notable difference is seen in spatial density maps with an increase in temperature for HMT-PMBI and show a more dense and enhanced distribution of water molecules compared to 300 K. Angular autocorrelation (torsional and rotational) decays relatively faster for PAImMM compared to HMT-PMBI. Water clusters around the skewed and extended configurations show a similar hydration pattern for both membranes. The mobility of the hydroxide ion is found to be relatively faster in HMT-PMBI compared to PAImMM. This work provides valuable atomistic insights that can inform the rational design of future ionene derivatives with enhanced ionic conductivity and structural robustness for electrochemical energy applications.