2-(methacryloyloxy)ethyl hydrogen maleate

2-(Methacryloyloxy)ethyl hydrogen maleate, commonly known as HEMA Maleate or Light Ester HO-ML (CAS 51978-15-5, EC 257-569-5), is a bifunctional reactive monomer carrying both a methacrylate and a maleate ester group within a single molecule. This dual-functionality distinguishes it from standard mono-functional acrylates and makes it relevant to controlled crosslink-density applications.

In UV- and peroxide-cured coating systems, the maleate half-ester acts as an electron-poor co-monomer that accelerates radical copolymerization with electron-rich vinyl ethers, enabling rapid cure at lower photoinitiator loadings. In adhesive and electronics encapsulant formulations, it introduces pendant carboxylic acid functionality after selective hydrolysis, improving adhesion to metal and oxide substrates.

HEMA Maleate is subject to REACH registration requirements for supply within the EU and should be handled under applicable CLP hazard classifications. It is typically available in liquid form supplied in drums or IBC containers; buyers should confirm inhibitor content and storage conditions with the supplier prior to procurement.