Properties & development of hydrogels

Hydrogels are a type of polymer network that can absorb and store large amounts of water [۱]. The hydrophilic groups or segments of the polymer network can be hydrated under neutral conditions to produce a gel structure [۲]. The cross-linked network structure prevents the dissolution of the hydrophilic polymer chains or segments. Hydrogels are solid-like and show nonflowing properties as inverted. They can also be described by their fluidics [۳]. In general, a low-concentration aqueous hydrophilic polymer solution with no entangled structures exhibits Newtonian mechanical behavior. Cross-linked hydrogels possess rheological properties with extremely high viscosity (۱۰۵ Pa s) and high elasticity (shear yield stress .۲۰۰۰ Pa), similar to solids. Due to their water insolubility, hydrogels are the research hotspots of swollen polymer networks, as well as their application studies. Hydrogels have been applied to a variety of fields, such as drought resistance in dry areas [۴], masks in cosmetics [۵], antipyretic stickers [۶], analgesic stickers [۷], agricultural films [۸], dew prevention agents in construction [۹], humidity control [۱۰], water-blocking agents in the petroleum industry [۱۱], dehydration of crude oil and refined oil [۱۲], dust suppressants in mining [۱۳], food preservatives [۱۴], thickeners [۱۵], pharmaceutical carriers in medical applications [۱۶], tissue engineering scaffolds [۱۷], wound dressings [۱۸], etc. It is worth noting that different application fields require different polymer materials.