Hydrogel

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Hydrogel is a network of polymer chains that are water-soluble, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are superabsorbent (they can contain over 99% water) natural or synthetic polymers.

Common uses for hydrogel are:

• In disposable diapers where they "capture" urine, or in sanitary towels
• Contact lenses (silicone hydrogels, polyacrylamides)
• medical electrodes using hydrogels composed of cross linked (polyethylene oxide, polyAMPS and polyvinylpyrrolidone)

Other, less common uses include:

• Breast implants
• Granules for holding soil moisture in arid areas
• Dressings for healing of burn or other hard-to-heal wounds
• reservoirs in topical drug delivery; particularly ionic drugs, delivered by iontophoresis (see ion exchange resin)

Common ingredients are eg. polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups.