Organic-inorganic hybrid composites and nanocomposites : an approach to develop polymer electrolyte membranes for proton exchange membrane fuel cells (PEMFCs)

Abstract

Two approaches of organic-inorganic hybrid composite membranes, i.e., (i) inorganic fillers functionalized with Krytox/Nafion® composite membranes; and (ii) clay silicate layers functionalized with sulfonic acid groups/ SPEEK (sulfonated polyether ether ketone) composite membranes are proposed for polymer electrolyte membrane fuel cell (PEMFC) applications. For the Nafion®-based composite membranes, a Nafion®-like-polymer chains, i.e., Krytox 157 FSL (carboxylic acid terminated perfluoropolyether), immobilized onto the surface of inorganic fillers, i.e., silica particles and montmorillonite, via silane coupling agent are designed for modifying filler surface to be miscible with Nafion®. The composite membranes prepared by solution casting process showing the proton conductivity maintained in the wide range of temperature up to 130 ๐c and the homogeneous membrane as observed by SEM proves US successful “like dissolves like” between Nafion® polymer chains and Krytox-modified fillers. In the case of the SPEEK-based composite membrane, montmorillonite treated with aminosilane coupling agent followed by reacting with 4-sulfophthalic acid is proposed as an approach to improve methanol crossover reduction and proton conductivity to be a potential material for direct methanol fuel cells (DMFCs).