A review on hydrogel: Classification, preparation techniques and applications

Hydrogel products are a class of polymeric materials with a hydrophilic structure that allows them to store huge amounts of water in three-dimensional networks. The presence of hydrophilic groups such as NH2, COOH, OH, CONH2, -CONH-, and -SO3H, as well as the capillary effect and osmotic pressure, contribute to the network's hydrophilicity. Weaker forces, like van der Waals forces and hydrogen bonds, can frequently act as cross-links, resulting in swelling networks that behave like hydrogels. Depending on their physical and chemical structure, hydrogels can be classified in a variety of ways. Material scientists and biological researchers continue to be fascinated by hydrogels today, and significant progress has been made in terms of formulations and applications. However, many articles and technical studies dealing with hydrogel products from an engineering standpoint were investigated to provide a broad overview of the technological features of this rapidly expanding interdisciplinary field of study. The major goal of this paper is to examine the literature on the technologies used in the creation, categorization, and use of hydrogels.