hydroksylietyylimetakrylaatti

Hydroksylietyylimetakrylaatti, known in English as hydroxyethyl methacrylate (HEMA), is an acrylate monomer widely used in polymer chemistry. It is the hydroxyethyl ester of methacrylic acid. The molecule contains a methacrylate vinyl group and a terminal hydroxyl group, which gives it hydrophilic properties and reactive functionality for subsequent polymerization.

As a vinyl monomer, HEMA polymerizes by free-radical addition to form poly(2-hydroxyethyl methacrylate) and can be crosslinked with multifunctional comonomers to create hydrogels and networks. It is commonly formulated with photoinitiators for UV curing or with thermal initiators such as AIBN or benzoyl peroxide. The hydroxyl group increases water compatibility, and polymers based on HEMA are typically transparent and flexible, with polyHEMA being notable for high water content.

Applications of HEMA span soft contact lenses, dental materials, wound dressings, coatings, and various hydrophilic polymers. In ophthalmology, polyHEMA was among the first widely used materials for soft contact lenses; in dentistry, HEMA-based adhesives and resins are used to improve bonding to dentin and enamel.

Production and handling: HEMA is primarily produced by esterification of methacrylic acid with ethylene oxide. To prevent premature polymerization during storage, inhibitors such as hydroquinone are added. Handling requires adequate ventilation and appropriate personal protective equipment. It is a skin and eye irritant and can cause sensitization; vapors are flammable and exposure to monomeric HEMA should be minimized.