Structure-property interplay of asymmetric membranes comprising of soft polydimethylsiloxane chains and hard silica nanomaterials

Abstract

Silica nanomaterials modified with monomolecular C18-alkyl silane or oligomeric dimethylsiloxane units were loaded in-situ during the formation of PDMS membrane. The small-angle neutron scattering (SANS) study was performed to probe structural compatibility between the modified silica and PDMS. The Ornstein-Zernike (OZ) and Debye-Anderson-Brumberger (DAB) models were excellently fit to the SANS data describing nanoscale structure morphology in terms of correlation length scales of the soft and hard segmental units. The polymeric chain was stretched or contracted depending upon the type and amount of silica incorporation. This indicated limiting amount of silica incorporation in the PDMS membrane structure depending upon structural compatibility between the silica and PDMS. The C18-alkyl silylated silica was found to be the best compatible with the membrane structure. The membrane with 30% (w/w) C18-alkyl silylated -silica loading exhibited the best performance in pervaporation separation of alcohol/water.