Methylimidazolium group - Modified polyvinyl chloride (PVC) doped with phosphoric acid for high temperature proton exchange membranes

Polymerization ionic liquid (PIL) is an important part of ionic liquid (IL), however, its poor film-forming property and low conductivity prevent it from being used as membrane electrolyte. Here, we overcome this limit by synthesizing a PIL directly from polyvinyl chloride (PVC), which reacts with N-methylimidazole to form methylimidazolium group-modified PVC (PVC-MIMCl). Besides that, PILs with different anions, such as PVC-MIMH2PO4, PVC-MIMCF3COO and PVC-MIMPF6 were obtained via anion exchange reactions. Phosphoric acid (PA) molecules were subsequently introduced into PIL membranes to improve the proton conductivity. PIL/PA membranes presented satisfactory tensile stress values owing to the support from PVC matrix. Moreover, the high proton conductivity was also obtained as expected. Thereinto, the proton conductivity of PVC-MIMCl/PA (1/5) membrane exceeded 1.0 x 10(-2) S cm(-1) at 160 degrees C under anhydrous conditions. Importantly, it remained around 8.0 x 10(-3) S cm(-1) more than 200 h at 130 degrees C. (C) 2015 Elsevier Ltd. All rights reserved.