Permeation Mechanism for a Thermo-Sensitive Switching-Functional Composite Membrane of Porous Glass and Hydrogel

Abstract

An attempt was made to prepare a thermo-sensitive membrane with switching ability. The membrane was made of porous glass and N-isopropylacrylamide gel, whose volume-phase transition is of a thermo-shrinking type. Permeation experiments have demonstrated that the composite membrane functioned as an ultrafiltration membrane, of which the cut-off molecular weight and solution permeation rate dramatically changed on the volume-phase transition. To make clear the permeation mechanism of the membrane, additional experiments were carried out, in which the diffusion rates of ³H-labeled water through the membrane were measured at various temperatures. Experimental results enabled the pore radii in the gel to be estimated. It is shown that the rejection characteristics of the membrane are predictable from the pore radii estimated.