Event
Special Seminar: Papatya Kaner, "Zwitterionic Copolymers"
Friday, July 13, 2018
11:00 a.m.
2168 AV Williams Building
Special Seminar
Zwitterionic Copolymers for Fouling Resistant and Responsive Membranes
Papatya Kaner
Ph.D. in Chemical Engineering, Tufts University
Abstract
Fouling is likely the most important obstacle to the use of membranes in many applications, especially in those that the feed contains high concentrations of organics such as oil and biomacromolecules. This work focuses on the use of zwitterionic copolymers, which are known to show excellent fouling resistance and hydrophilicity, to enhance the fouling resistance of ultrafiltration (UF) membranes and/or incorporate responsive features into these systems that can enable self-cleaning mechanisms. One approach to incorporate these features into UF membranes is during their manufacture, by blending a commodity polymer with a zwitterion containing copolymer. We studied the effect of the skeletal architecture of zwitterionic additives in membrane properties, by comparing zwitterionic copolymers with two different architectural structures, random and comb-shaped. We showed that both additives lead to a water permeance five times that of the additive free membrane. However, comb additive containing membrane exhibits a more prominent ionic strength responsive change in its surface nanostructure and permeance, in addition to its better resistance to oil fouling and protein adhesion. As another approach, we developed a novel self-cleaning, photoresponsive membrane that is capable of removing pre-deposited foulant layers upon changes in surface morphology in response to UV or visible light irradiation. This membrane was prepared by coating a porous support membrane with a thin layer of a comb-shaped graft copolymer with photoreactive side-chains. Before any photo-treatment, the as-coated membrane allows the adsorption of organic solutes on its surface, reducing flow rate. Once exposed to UV light, conversion of hydrophobic spiropyran groups to hydrophilic merocyanine groups leads to the release of adsorbed molecules and full recovery of the initial water flux. Lastly, we developed selective thin films whose morphology and function arise from the self-assembled nanostructure of the zwitterionic comb copolymers. Thin film morphology showed hierarchical features including 17 ± 5 nm spherical micelles along with larger nanopores of 85 ± 45 nm, which arose from the self-assembly of the copolymer in this bilayer system. In addition, the film proved ionic strength responsive permeation in ultrafiltration range with a pore density as high as 1013 pores/m2
Biography
Papatya Kaner has recently received her Ph.D. in Chemical Engineering from Tufts University. She obtained her B.Sc. in Chemical Engineering from Istanbul Technical University (ITU), Turkey in 2009, and her M.Sc. in Chemical Engineering from Florida State University in 2011. Her M.Sc. studies focused on fundamental structure-property relationships that correlate polymer chemistry and architecture with polymer crystallization. She was awarded the Dean’s Fellowship from Tufts University for her Ph.D. studies, which were conducted under supervision of Prof. Ayşe Asatekin. Her research involved designing polymeric materials that self-assemble into functional nanostructures for various applications including water filtration membranes. She developed stimuli-responsive water filtration membranes with excellent fouling resistance by using custom-designed zwitterionic copolymers. In addition, she implemented comb-shaped zwitterionic copolymers to develop porous thin films with nanoscale, hierarchical morphology and tunable pore size. Currently, she has five first author papers in leading scholarly journals, and is co-inventor on two patent applications. Media outlets such as Phys.org and Membrane Quarterly magazine have featured her work on membranes.
