Analysis of Pore Size Using a Straight-Pore Molecular Recognition Ion Gating Membrane

Abstract

An analysis of the water permeability of a molecular recognition ion gating membrane was performed. The ion gating membrane shows outstanding water permeability switching properties in response to specific ion concentrations, using an ion-responsive polymer consisting of thermosensitive poly(N-isopropylacrylamide) and crown ether moieties, grafted onto a porous substrate pore surface. To investigate the precise properties of the membrane, a polycarbonate track-etched membrane having straight pores with a narrow pore size distribution was used as the substrate, and the ion responsive polymer was grafted onto its pore surfaces. The gating property of the prepared membrane was examined as a function of temperature, specific ion concentration, and filling ratio. Estimates of pore size and dimension of the grafted polymer were obtained using the Hagen–Poiseuille equation. We found that the grafted ion-responsive polymer shows drastic dimensional changes in response to temperature and specific ion concentrations.