The influence of solvent properties on the performance of polysulfone/β-cyclodextrin polyurethane mixed-matrix membranes
Journal of Applied Polymer Science
Department of Applied Chemistry, University of Johannesburg, Doornfontein 2028, South Africa; Department of Civil and Environmental Engineering, California NanoSystems Institute, Los Angeles, CA 90095-1593, United States
This study investigates the effect of solvent properties on the structural morphology and permeation properties of polysulfone/β-cyclodextrin polyurethane (PSf/β-CDPU) mixed-matrix membranes (MMMs). The membranes were prepared by a modified phase-inversion route using four different casting solvents [dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), and N-methyl-2-pyrrolidone (NMP)]. While DMSO-based membranes demonstrated particularly high permeability (ca 147 L/m2h.bar), their crystallinity was low compared to MMMs prepared using DMA, DMF and NMP due to the formation of thin active layers on their surfaces. Cross-sectional morphology revealed that the MMMs have a dense top skin with finger-like inner pore structures. Membranes prepared using NMP displayed the highest hydrophilicity, porosity, and crystallinity due to the low volatility of NMP; DMF membranes exhibited superior mechanical and thermal stability due to its (DMF) high hydrogen bonding (δH) values. Thus, the morphological parameters, bulk porosity, and flux performance of MMMs have a significant inter-relationship with the solubility properties of each solvent (i.e., δH, density, volatility, solubility parameter). © 2013 Wiley Periodicals, Inc.
Cross-sectional morphology; Dimethyl sulfoxide (DMSO); Mixed-matrix membranes; Morphological parameters; N-methyl-2-pyrrolidone; Permeation properties; Solubility parameters; Structural morphology; Blending; Cyclodextrins; Dimethyl sulfoxide; Hydrogen bonds; Morphology; Organic solvents; Polyurethanes; Porosity; Solubility; Solvents; Membranes