Synthesis of Copolymer Hydrogel Networks to Determine the Effects of Network Architecture on Water Structure and Hydration Processes

摘要

Hydrogels are capable of absorbing many times their weight in water but are insoluble in water due to their crosslinked nature, making them ideal materials for use in biomedical applications such as drug delivery systems. Within water, hydrogel networks play a pivotal role in dictating network properties such as mechanical stability, permeability, and network architecture. Three structural states of water (bound, restricted, and free) exist within hydrogel networks, and are determined by the degree of hydrogen bonding that occurs between molecular water and the network. The purpose of this study is to gain a fundamental understanding of the influence of structural parameters such as crosslink density, hydrophilic/hydrophobic content, and hydrophilic monomer identity on water content, structure, and hydration processes (e.g., hydration and dehydration) of copolymer hydrogels. Acrylamide-based glycomonomers containing a stereospecific pendant galactose moiety and dimethyl acrylamide were independently used as the hydrophilic component in hydrogels synthesized via UV initiated free radical polymerization. A siloxane containing monomer, 3-acrylamidopropyl tris(trimethylsiloxy)silane was incorporated to tailor the level of hydration as well as the distribution of bound water in varying network architectures. Water structure and hydration processes of varying network architectures were characterized via thermogravimetric analysis and dynamic scanning calorimetry. Significant differences in equilibrium water and bound water content were observed as a function of hydrophobic content and crosslink density.