Effect of morphology of mesoporous silica on characterization of protic ionic liquid-based composite membranes

Abstract

Effects caused by the morphology of mesoporous silica on the characterization of protic ionic liquid-based composite membranes for anhydrous proton exchange membrane applications are investigated. Two types of SBA15 materials with platelet and fiberlike morphologies are synthesized and incorporated into a mixture of polymerizable monomers together with an ionic liquid (IL)[1-butyl-3-methylimidazolium bis(trifluoromethane sulfone)imide (BMIm-TFSI)] to form new conducting membranes using an in situ photo crosslinking process. Incorporation of a defined amount of fiber-shaped SBA 15 and platelet 15 significantly increases the ionic conductivity to between two and three times that of a plain poly(methyl methacrylate) (PMMA)/IL membrane (2.3 mS cm(-1)) at 160 degrees C. The protic ionic liquid (PIL) retention ability of the membranes is increased by the capillary forces introduced by the mesoporous silica materials, while ionic conductivity loss after leaching test is retarded. The highest ionic conductivity (5.3 mS cm(-1)) is obtained by incorporating 5 wt% of P-SBA 15 in the membrane to about six times that of plain PMMA/IL membrane (0.9 mS cm(-1)) at 160 degrees C after leaching test. (C) 2011 Elsevier B.V. All rights reserved.