Introduction to Hydrogels

Abstract

Hydrogels are a class of crosslinked polymers that, due to their hydrophilic nature, can absorb large quantities of water. These materials uniquely offer moderate-to-high physical, chemical, and mechanical stability in their swollen state. The structure of a hydrogels can be designed for a specific application by selecting proper starting materials and processing techniques. Since the equilibrium swelling capacity of a hydrogels is a balance between swelling and elastic forces, hydrogels with different swelling capacities can be designed by modulating the contribution of individual forces. Certain hydrogels respond to the changes in environmental factors by altering their swelling behavior. This chapter explains the evolution of hydrogels as a new class of the crosslinked polymers, the hydrogels structures, swelling forces, swelling kinetics, types of water in a swollen hydrogels, and composite properties of hydrogels materials.