Triethylene glycol dimethacrylate is used as a cross-linking agent in the synthesis of poly (methacrylic acid-g-ethylene glycol) hydrogels which shows large changes in swelling due to changes in pH, temperature and solvent composition. They are also used as divinylic methacrylic monomers which are widely used to form copolymers with divinylbenzene (DVB) and glycidyl methacrylate (GMA) or hydroxyethyl methacrylate (HEMA) comonomers.