Improving water selectivity of poly (vinyl alcohol) (PVA) - Fumed silica (FS) nanocomposite membranes by grafting of poly (2-hydroxyethyl methacrylate) (PHEMA) on fumed silica particles

Nanocomposite membranes were prepared by incorporation of PHEMA-grafted FS particles with PVA membrane. The grafted-PHEMA promoted a dispersion of FS particles within PVA matrix as revealed by TEM. As a result, the tensile properties of the nanocomposite membranes including Young's modulus and strength were enhanced. PHEMA-grafted layer on FS particles also strengthened the adhesion at FS-PVA interface causing a shift of T-g of the nanocornposite membranes to higher temperature compared with T-g of PVA. On complete swelling in water, T(g)s of the nanocomposite membranes decreased to approximately that of the water swollen PVA membrane. Dynamic swelling of the nanocomposite membranes suggested an increase in the water diffusion coefficient with increasing PHEMA-grafted FS loading and PHEMA grafting. Water uptake of PHEMA-grafted FS filled membranes was increased compared with those of unfilled PVA membrane. Employing the pervaporation technique, the dehydration of water-acetone mixture was studied, thus revealing an enhancement of water permeability and selectivity in the presence of PIEMA-grafted FS particles. (C) 2014 Elsevier Ltd. All rights reserved.