2 Hydroxy Ethyl Methacrylate

Hydroxyethylmethacrylate or HEMA is the organic compound with the formula HOCH2CH2O2CC(Me)=CH2. It is a colorless viscous liquid that readily polymerizes. HEMA is a monomer that is used to make various polymers. Polyhydroxyethylmethacrylate is hydrophobic; however, when the polymer is subjected to water it will swell due to the molecule's hydrophilic pendant group. Depending on the physical and chemical structure of the polymer, it is capable of absorbing from 10 to 600% water relative to the dry weight. Because of this property, it was one of the first materials to be successfully used in the manufacture of soft contact lenses. When treated with polyisocyanates, poly(HEMA) makes a crosslinked polymer, an acrylic resin. that is a useful component in some paints.