Metakrilat

Metakrilat refers to esters of methacrylic acid. Chemically, metakrilat denotes compounds with the general structure CH2=C(CH3)COOR, where R is an alkyl group. They are monomers that form poly(methacrylate) polymers by free-radical polymerization.

Common examples include methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA) and hydroxyethyl methacrylate (HEMA). MMA is widely used to make polymethyl methacrylate (PMMA), a transparent, rigid thermoplastic employed in lenses, glazing and signage. Methacrylate polymers are also used in coatings, adhesives, dental resins and contact lenses.

Production typically involves esterification of methacrylic acid with the corresponding alcohol or transesterification. Industrial polymerization is carried out by radical initiators such as azobisisobutyronitrile, benzoyl peroxide or redox systems, in bulk, solution, suspension or emulsion, depending on the desired material.

Properties vary with the alkyl group R. MMA is a colorless liquid at room temperature; methacrylate polymers generally offer high clarity, weather resistance and hardness. They can exhibit a high refractive index and good optical properties, making them suitable for lenses and displays. In coatings, they provide adhesion and chemical resistance.

Methacrylate monomers are irritants and skin sensitizers; exposure should be minimized. They may polymerize exothermically if heated or contaminated, so inhibitors are added to storage batches and containers should be kept closed with adequate ventilation during handling.