Selective water‐permeable channels induced by polystyrene brushes within hairy nanocellulose/cellulose acetate membrane

Abstract

Hairy nanocellulose (NC) was prepared by in‐situ admicellar polymerization of styrene on NC surface in the presence of cetyltrimethylammonium bromide through a stepwise fashion. It was also tried to achieve three hairy NCs with different polystyrene (PS) brush contents (i.e. 40, 50, and 80%) through altering monomer initial concentration. Then, NC and three hairy NCs were separately added into cellulose acetate (CA) solutions to fabricate membranes via the phase inversion technique. Transmission electron microscope images show that NC and three hairy NCs are spherical‐shaped nanoparticles. Results of Fourier transform infrared spectra provide clear evidence of PS brush being attached to the NC surfaces. Thermal gravimetric analysis confirms that increasing styrene initial concentration leads to enhanced PS content of hairy NCs. Results also elucidate that dispersions of prepared hairy NCs are highly stable even at high loading levels. It was found that incorporation of 1 wt% hairy NC with optimum brush content of 50% within CA membranes results in the increasing membrane water permeability from 7 to 40 l/m2 hr with no change in its selectivity. Indeed, new interactions induced by PS brushes at hairy NC/CA interfaces result in the creation of connected channels at the interfaces which facilitate water transport through the membrane. This study provides insights into the key role that PS brushes play in overcoming the dispersion problems of NC in nonpolar media and offers guidelines to tailor channels within hairy NC/CA membrane for enhanced filtration performance. Copyright © 2017 John Wiley & Sons, Ltd.