Properties and development of hydrogels

Hydrogels are cross-linked polymeric networks prepared from hydrophilic polymers, which can absorb and retain a high water content while maintaining their three-dimensional integrity. Hydrogels are very important in medical and pharmaceutical applications, personal care products, environmental protection, the food industry, and agriculture. The diverse properties of natural polymers mean that they are an ideal skeleton for the preparation of hydrogels. In the last 2-3 decades there have been many reported papers that highlight hydrogels based on natural polymers due to their excellent properties-biodegradable, biocompatible, environmentally friendly, and flexible, similar to natural tissue. The aim of this chapter is to give a brief introduction to the structure, properties, classification, and development of hydrogels.