PERMEATION MECHANISM FOR A THERMOSENSITIVE COMPOSITE MEMBRANE COMPOSED OF POROUS-GLASS AND N-ISOPROPYLACRYLAMIDE

A previously proposed method for preparing a composite membrane of hydrogels and porous inorganic substances was used for the synthesis of a thermo-sensitive membrane with switching ability. The membrane was made of porous glass and N-isopropylacrylamide gel, which has a volume-phase transition of the thermo-shrinking type. Permeation experiments demonstrated that the composite membrane functioned as an ultrafiltration membrane, the cut-off molecular weight and solution permeation rate of which dramatically changed on 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. From the experimental results the pore radii in the gel could be estimated. It is shown that the rejection characteristics of the membrane are predictable from the pore radii estimated. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.