Poly (N-Isopropylacrylamide)-Based Microgels for Contaminant Removal from Water

Abstract

Polymer based materials have been utilized widely for applications that can be of benefit to human health and the environment. This thesis covers the general scope of polymer materials on bases of star-shaped polymer and temperature-responsive poly (N-isopropylacrylamide) (pNIPAm) microgels, their co-functional polymers, their assemblies, and their applications as an anti-fouling coating layer on membrane surfaces in water remediation systems. Chapter 1 gives a brief introduction of anti-fouling membrane and stimuli-responsive polymers, their assemblies and applications, and the background on polymer material coated anti-fouling membranes. Chapter 2 focuses on investigating the anti-fouling properties with the filtration system using star-shaped polymer composed membranes. Star-shaped polymers with a silica core have been designed to enhance the coating stability and anti-fouling properties. The anti-fouling performance could be tuned by varying the star-shaped polymer compositions in the membrane. Chapter 3 focuses on optimizing the pNIPAm based microgel coating on a polyethersulfone (PES) membrane through a new coating strategy. In this work, the microgel coating stability was investigate by tuning the microgel sizes and coating processes. With optimized microgel sizes and coating procesess, the anti-fouling performance also was optimized by varying the charge group (acrylic acid, AAc) compositions in the microgel. A long-term filtration was operated to confirm the coating stability with an AAc composited microgel coated membrane. As a further study of the AAc composited microgel coating in water remediation applications, Chapter 4 discussed the idea of microgels as sorbents during the filtration process. Chapter 4 focuses on investigating the absorption capacity of pNIPAm based microgel coatings for water remediation application. The interactions between the microgel and metal ions were studied by observing the microgel shrink/swell behavior in the metal ion solution. The metal ion concentration changes obtained from ICP-OES during the filtration reveal the absorption capacity.