The chemical crosslinking of polyelectrolyte complex colloidal particles and the pervaporation performance of their membranes

Water dispersible polyelectrolyte complexes (PECs) of sodium carboxymethyl cellulose (CMCNa) and poly(diallyldimethylammonium chloride) (PDDA) were crosslinked via glutaraldehyde (GA) to improve the water resistance and stability performance of their pervaporation membranes. Relative crosslinking degrees (RCDs) of PECs with different GA contents were obtained by Fourier Transform Infrared Spectroscopy (FT-IR). Free volume of crosslinked PECs membranes (CPECMs) was examined by Doppler Broadening Energy Spectroscopy (DBES). The surface hydrophilicity and morphology of CPECMs were investigated by dynamic contact angle (DCA) and atomic force microscope (AFM), respectively. CPECMs were subjected to pervaporation dehydration of aqueous isopropanol mixtures. It was found that CPECMs showed very high water resistance, super permeability and good selectivity. Crosslinked PECs membrane with 0.5 wt% GA (CPECM0.5) showed a permeate flux of 21.2 kg/(m2 h) and water content in permeate of 98.1 wt% in dehydrating 50 wt% aqueous isopropanol mixture at 70 °C. Moreover, good long time stability of CPECMs for dehydration of aqueous isopropanol mixture was also observed. These excellent performance are attributed to the chemical crosslinking of polyelectrolyte complex colloidal particles.

► Polyelectrolyte complex colloidal particles can be crosslinked by solution blend.
► The needle-shaped microstructures exist in crosslinked PEC membranes (CPECM).
► Free volume of CPECM decreases with increasing relative crosslinking degree.
► The best CPECM shows long time stability in separating 50 wt% water–isopropanol mixture.