Nanoscale homogeneity of silica–poly(vinyl alcohol) membranes by controlled cross-linking via sol–gel reaction in acidified and hydrated ethanol

Abstract

Organic–inorganic hybrid membranes in which nanoscale hybrid domains create preferential pathways for selective permeation exhibit excellent performance in separation processes. Herein, a sol–gel reaction synthesis route in acidified and hydrated ethanol to prepare a silica–poly(vinyl alcohol) hybrid membrane of nanoscale homogeneity is reported. A ²⁹Si NMR study was performed on the membrane samples to probe the connectivity of SiO₄ tetrahedra in the cross-linking hybrid networks while the small-angle scattering study revealed the nanostructure of the silica–polymer hybrid. TEM, DSC, IR, TGA, XRD and swelling studies were performed to study other physico-chemical properties of the membrane. The hybrid membrane exhibited superior water permeability (96 L m⁻² h⁻¹ μm) to other reported membranes in the pervaporation desalination of saline water of 2000 ppm NaCl.