Ethanol-Responsive Characteristics of Polyethersulfone Composite Membranes Blended with Poly(N-isopropylacrylamide) Nanogels

Ethanol-responsive smart membranes with different microstructures are prepared from blends of polyethersulfone (PES) and poly(N-isopropylacrylamide) (PNIPAM) nanogels by immersion precipitation phase inversion method in a convenient and controllable manner. The introduction of PNIPAM nanogels forms the microporous structures on the surface of the top skin layer and on the pore walls of the finger-like porous sublayer of membranes. The ethanol-responsive characteristics of the proposed PES composite membranes are systematically investigated. With increasing ethanol concentration in the range from 0 to 15 wt %, the transmembrane flux of ethanol solution increases. The microstructures and the resultant ethanol-responsive characteristics of the composite membranes can be regulated by the content of PNIPAM nanogels blended in the membranes. The more the content of PNIPAM nanogels blended in the membranes, the more the number of the submicron pores is, and thus the better the ethanol-responsive characteristics of the composite membranes. The proposed ethanol-responsive smart membranes are expected to be combined with the traditional pervaporation membranes as a smart vavle to achieve continuous and highly efficient ethanol production during the biological fermentation. The preparation technique and results in this study provide valuable guidance for further design and the industrial-scale fabrication of novel composite membranes for application in ethanol separation systems. (C) 2014 Wiley Periodicals, Inc.