Abstract:Polymeric membranes produced by Non-solvent Induced Phase Separation (NIPS) have been extensively used across a wide array of microfiltration and ultrafiltration processes. However, despite their broad applications, current fabrication processes are largely empirical, determined by trial and error. Better insights into the factors affecting membrane structure and morphology would be of great use. To that end, Dissipative Particle Dynamics (DPD), a coarse-grained mesoscale simulation method, was used to simulate the membrane formation process involving polyethersulfone (PES) in methyl-2-pyrrolidinone (NMP) solvent with H2O as an anti-solvent. The DPD simulations were performed for a total of several million beads and over several microseconds. The interaction forces and associated parameters between these beads are derived from Flory-Huggins thermodynamic theory and continuum transport equations. The effects of PES polymer concentration (8-16% (v/v)) and molecular weight (chain length with degree of polymerization of 60, 90, 135) on the membrane structure and morphology were investigated. In addition, the effects of additives such as polyethylene glycol (PEG) and its concentration on the thermodynamics and kinetics of PES membrane formation were investigated. Membrane morphology was found to depend strongly on the amount of additive included.
Bio:Xianghong Qian is a professor in the Department of Biomedical Engineering at the University of Arkansas at Fayetteville (UAF). Prior to joining UAF, she was a faculty member from the Department of Mechanical Engineering at Colorado State University. She has a BS degree in Chemistry from Nanjing University, China and a Ph.D. in Theoretical Chemistry from the George Washington University, USA. She did her postdoctoral research in Condensed Matter Theory at the Max-Planck Institute for Microstructure Physics, Germany. Dr. Qian’s current major research interests focus on membrane-related processes including the purification of biopharmaceuticals during downstream processing, catalytic conversion of biomass to biofuels, carbohydrate chemistry, smart polymers for membrane applications and membrane formation using complementary experimental and modeling approaches. She is the recipient of 2009 NSF CAREER award and has over 90 peer-reviewed journal publications, 9 book chapter publications and 3 patents.