Influence of crystal morphology of 1H-1,2,4-triazole on anhydrous state proton conductivity of sulfonated bisphenol A polyetherimide based polyelectrolytes

In this study, new anhydrous proton conducting polyelectrolytes were prepared based on sulfonated bisphenol A polyetherimide (SPEI) and 1H-1,2,4-triazole (Taz) as a solid state proton solvent. The effect of degree of sulfonation and triazole concentration on size, shape and dispersibility (crystal morphology) of triazole crystals in sulfonated polyetherimide were examined and correlated with proton conduction. At a constant triazole weight percent, increased sulfonation level caused enhanced nucleation density, reduction of crystallite size and their uniform distribution throughout SPEI matrix. The decrease in size was responsible for the depression of triazole melting temperature. Proton conduction through structure diffusion occurred effectively within the smaller size crystals due to the improved molecular mobility.