Date of Award

Fall 12-1-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Sarah E. Morgan

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Sergei I. Nazarenko

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Robert Y. Lochhead

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

James W. Rawlins

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Gopinath Subramanian

Committee Member 5 School

Polymer Science and Engineering

Abstract

Glycohydrogels have recently gained considerable interest as biocompatible and high water content hydrogels that have similar physicochemical nature to the cell membrane, making them ideal materials for targeted biomedical and personal care applications (e.g., drug delivery systems, biosensors, and contact lenses). Regardless of the specific application, water-polymer and water-water hydrogen bonding interactions have been shown to dictate hydration stability and diffusional properties in traditional hydrogel architectures (e.g., crosslinked HEMA). However, due to the development of glycohydrogel materials within the past two decades, most literature focuses on synthetic techniques and general hydration characteristics. Furthermore, scant literature examines the effect of hydrophobically modified glycohydrogels on hydrogen bonding modes and diffusion characteristics.

This dissertation explores the fundamental physicochemical nature of hydrophobically modified glycohydrogels containing pendant galactose and siloxane moieties. An experimental and simulation approach was utilized to examine the effect of amphipathic balance and crosslink density on bound water content, water mobility, and desorption kinetics for hydrophobically modified glycohydrogels swollen in water. We found that bound water can be tuned in high water content glycohydrogels with the addition of hydrophobic comonomers. Finally, the sol/gel transition kinetics and development of network modulus was monitored via UV-rheology for a series of homopolymer and copolymer glycohydrogels containing systematically varied crosslinker and hydrophobic comonomer loadings. The viscoelastic properties of the as-prepared hydrogels as a function of frequency were used to reveal characteristic features (e.g., loss and storage modulus) associated with the type of network architecture developed. Homopolymer glycohydrogels exhibited viscoelastic behavior suggestive of the formation of hydrogen-bonded clusters among pendant saccharide groups. Addition of hydrophobic comonomers aided in the dissociation of these clusters but also significantly reduced the elastic modulus of the glycohydrogel network.

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