Mechanical properties and pervaporation separation performance of CTAB-modified cage-structured POSS-incorporated PVA membrane

摘要

Permselective polymeric membranes are important materials for the efficient separation of organic solvents and azeotropic mixtures. In this work, we address an effective strategy to the fabrication of novel high-performance membranes of crosslinked poly(vinyl alcohol) (PVA) by incorporating chemically modified cage-structured polyhedral oligomeric silsesquioxane (m-POSS) through solution casting method. The fabricated PVA/m-POSS system showed excellent mechanical stability as well as good pervaporation performance for the separation of isopropanol (IPA)-water azeotropic mixture. Scanning electron micrographs and atomic force microscopy analysis revealed the homogeneous dispersion of m-POSS in PVA matrix. Differential scanning calorimetric studies showed the rigidification of crosslinked PVA matrix by the incorporation of m-POSS. Tensile strength and Young's modulus of PVA matrix were increased remarkably to 200% and 740%, respectively, in the presence of 5wt% of m-POSS. Moreover, the membranes exhibited excellent water selectivity, hydrophilicity and excellent anti-fouling properties compared to traditional hydrophilic membranes. At lower filler loading (1.0wt%), 300% and 200% increase in selectivity and permeance were observed for PVA/m-POSS system over crosslinked PVA. The excellent mechanical properties and other comprehensive properties revealed the potential of the PVA/m-POSS system for the effective separation of azeotropic IPA-water mixture. Modified Maxwell-Stefan model was applied for the theoretical estimation of permeation flux and it was in good agreement with the experimental findings.