Highly size-selective ionically crosslinked multilayer polymer films for light gas separation

Hydrogen separation via polymer membranes is hindered by low selectivity and weak mechanical strength. In this study, the authors present an ionic cross-linked polymer film, formed using layer-by-layer assembly of a branched polyethylenimine and poly(acrylic acid), capable of combining exceptionally high hydrogen selectivity with remarkable mechanical  properties at gas permeabilities in excess of the traditional “upper bound” associated with homogeneous polymeric membranes. The excellent performance of hydrogen selectivity and mechanical strength represents a significant breakthrough in the realization of low-cost, highly manufacturable polymer membranes for hydrogen purification.