Cross-linked hydrogel networks

Rathna, G.V.N., D.V.M. Rao and PR. Chatteqi, Water-induced plastisizadon of solution cross-linked hydrogel networks energetics and mechanism. Macromolecules, 27 (1994) 7920-7922. 

Hydrogels are 3D cross-linked polymer networks. They can withstand acid conditions and release the entrapped drug molecules. Purdue University researchers have used a poly[methacrylic acid-g-poly(ethylene glycol)] hydrogel to encapsulate insulin, which could be released by pH trigger. 

Hydrogels are physically or chemically cross-linked polymer networks swollen with large amounts of water. Due to their crosslinked nature, these gels do not dissolve in aqueous media but contain an enormous amount of solvated water molecules within the entangled polymer chain matrix. Hydrogel properties are reviewed elsewhere in this book. This chapter is dedicated to a unique hydrogel family that responds to... 

Many materials are employed in the production of soft contact lenses. The material with the widest application in the industry is HEM A [13]. HEM A became a popular soft contact lens because of its clarity, comfort, good vision, and excellent wetting characteristics. HEMA is a hydrogel, and hydrogels are cross-linked polymer networks that are swollen in water. Hydrogels are typically classified by whether they are neutral or ionic. Anyone who has had a piece of dirt in the eye understands the need for good wettability when it comes to a contact lens. The wettability of a soft contact lens in the ocular environment is a function of the surface chemistry while it is hydrated, which determines the biocompatibility of the lens [6]. A lens surface that does not wet will cau.se discomfort and potentially increased deposits. These deposits can affect vision and the physical properties of the lens [3,4]. The major drawback of HEMA is the permeability of the material to oxygen [12]. Extended wear can result in increased vascularization of the cornea... 

Hydrogels are cross-linked polymeric networks that have the ability to hold water within the cross-linked polymeric chains. They have been used extensively in biomedical applications such as drug... 

---