Functionalized Thermo-responsive Polymer Core-shell Materials for use in Controlled Dye Release, Thin-film Composite Membranes, and Water Desalination

Abstract

This thesis focuses on the varied applications of core-shell structured stimuli- responsive polymer materials and their applications in water treatment. The relevant background and introduction to stimuli-responsive polymers, core-shell particles and morphologies, and membrane separations systems is detailed in Chapter 1. Chapter 2 explores the effect of shell thickness on the uptake and release of dye loaded into pNIPAm-based microgels. The modified core is designed for the uptake of oppositely charged dye species where the release of the dye can be triggered by changes in pH. The release profiles from the loaded microgels free in solutions as well as immobilized on a gold surface at temperatures below and above the LCST was observed. Chapter 3 utilized a similar morphology core-shell nanogel where a poly(N-3- aminopropyl)methacrylamide polymer shell was added to a pNIPAm core that could be covalent crosslinked to the selective polyamide layer used in thin-film composite (TFC) membranes. The feed temperature of the pressure-driven nanofiltration membranes was heated above the LCST of the nanogels to observe the changes in flux and salt rejection when the nanogels were incorporated within the polyamide structure. Further, the nanogels were localized on the surface of the polyamide to observe the impact they had on improving the antifouling properties of the TFC membrane. The final project detailed in Chapter 4 utilizes a spherical pNIPAm hydrogel coated in the polyamide skin layer to create a self-driven water filtration system. The clean water absorbed by the hydrogel can be recovered by heating the hydrogels. The salt rejection was evaluated by ICP-AES and confirmed excellent rejection performances for the optimized polyamide layer against a variety of salt species.