2-Hydroxyethyl Methacrylate, often recognized by its abbreviation HEMA, has carved out a niche in chemical manufacturing and polymer science. This compound, based on its IUPAC name 2-Hydroxyethyl methacrylate, comes under the broader category of methacrylate esters. Its CAS number is 868-77-9 and it carries the HS Code 29161400. HEMA is a coveted raw material, known for transforming into robust, long-lasting, and specialty polymers through radical polymerization processes.
HEMA’s molecular formula is C6H10O3, and its molecular weight falls at 130.14 g/mol. The structure features a methacrylate backbone, functionalized by an ethylene glycol chain capped by a hydroxyl group, producing a balance between hydrophilic and hydrophobic regions. Its structural formula, CH2=C(CH3)COOCH2CH2OH, highlights both the reactivity of the double bond from the methacrylate and the polar, hydrogen-bonding nature of its hydroxyl group. This dual character influences its versatility and solubility, letting HEMA blend into both polar and nonpolar environments. Visuals of pure HEMA often show a clear, viscous liquid, though commercial samples may appear yellowish from trace inhibitors or impurities.
HEMA is typically encountered as a colorless to pale yellow liquid at room temperature, with a faint, somewhat acrid odor. The density hovers around 1.07 g/cm3. Its melting point stands at -12°C, and it only begins to boil at temperatures well above 200°C, usually at about 213°C under normal pressure. Whether in flakes, powder, pearls, or even a highly pure crystal form, the product demonstrates consistent viscosity, especially as temperatures dip below 20°C — a feature critical in polymer chemistry because of its handling requirements. HEMA blends easily with a range of solvents, including water, alcohol, and organic liquids, thanks to its hydrophilic ethoxy group. The hydroxyl value can affect its copolymerization behavior. In terms of packaging, HEMA arrives most often in liquid bulk or smaller drums to shield it from moisture and UV exposure. Bulk densities are defined for storage, typically around 1.12 g/mL at 20°C.
Buyers find HEMA available in various grades and purity levels, depending on the intended application. Standards often demand a minimum purity of 97% or greater, with water content kept below 0.3%. The product arrives stabilized with a small dose of a polymerization inhibitor, such as hydroquinone, to preserve its shelf life. Some suppliers also purvey flakes, solidified pearls, or granules for users demanding precise dosages in solid manufacturing processes, though the bulk of commercial trade involves liquid solutions. HEMA can be formulated as a solution in water or alcohol for faster reactivity in applications like medical hydrogels, adhesives, or coatings. Beads or pearls may appear in the dental supply chain, where measured polymerization is critical in dental resins or bone cements.
HEMA’s hydrophilic character sets it apart, allowing high water uptake and swelling when embedded in crosslinked polymers. This property underpins its widespread adoption in soft contact lenses and drug delivery hydrogels. Formulators value its ability to confer flexibility, toughness, and biocompatibility to finished products. In paints, adhesives, and surface coatings, HEMA acts as a building block for copolymers, delivering strong adhesion, chemical resistance, and improved mechanical properties. Medical device manufacturers integrate HEMA into specialist solutions where tissue compatibility and controlled water absorption make a difference. The compound bridges the space between hard thermoplastic acrylics and softer, water-rich materials, letting innovators tailor performance at a molecular level.
Working with HEMA requires care — this liquid can irritate skin and eyes, and inhalation of mists or prolonged exposure risks sensitization reactions. Most safety data sheets classify HEMA as harmful in concentrated forms. Operators need gloves, goggles, and ventilation, with splash protection mandatory during transfer or mixing. Storage needs strict temperature control and inhibitor management to avoid spontaneous polymerization, especially when drum temperatures rise or lids are left loose. There’s a marked flammability risk, though less so than many solvent-based monomers, thanks to its high boiling point and moderate vapor pressure. Though not considered acutely toxic, spills and leaks can threaten aquatic systems, and safe disposal follows strict chemical waste regulations. Handling procedures draw a sharp line between "useful raw material" and "potential occupational hazard."
HEMA production uses raw materials from the reaction of methacrylic acid and ethylene oxide or ethylene glycol, so global supply depends on feedstock costs and petrochemical capacity. The chemical supply chain for specialty monomers like HEMA has faced volatility, driven by tightening regulatory oversight in Europe and North America. Sustainability and responsible sourcing have gained ground as consumers grow curious about the origins and environmental lifecycle of chemical products. Engineers try to lower emissions, improve product purity, and minimize the formation of byproducts or waste in both batch and continuous process plants.
HEMA’s significance in modern industry can’t be overstated. Many have seen its impact through safer, more comfortable medical implants or advanced performance coatings. As someone who’s used HEMA-based adhesives, the balance of rapid polymerization and strength stands out. Product safety deserves more than basic warnings; regular updates to safety protocols, employee training, and closed system development together lower risks on the shop floor. For waste and environmental exposure, developing recycling strategies for HEMA-based polymers remains challenging. Closed-loop systems and better neutralization chemistries could carve out real advances. On the regulatory front, harmonizing chemical safety data and international shipping laws would streamline crossborder supply, especially for research or pharmaceuticals. As demand keeps growing in healthcare and electronics, oversight will matter even more — but so does technical know-how. Those at the lab bench and in plant operations need a full picture of the material: how it behaves, how it reacts, and how to store and use it safely.
