ABSTRACT
A hydrogel is a three-dimensional network of hydrophilic polymer chains held together by chemical bonds (i.e., covalent bonds) or physical bonding (e.g., hydrogen bonding, ionic interaction, and hydrophobic association) (1). Due to the hydrophilic nature of the polymer chains, the network is able to absorb water within its structure and swell without dissolving while maintaining the overall structure. Table 1 lists some examples of commonly used polymers that can be crosslinked to make hydrogels.
