Synthesis and flame-retardancy of UV-curable methacryloyloxy ethyl phosphates

Tris[2-methacryloyloxy ethyl] phosphate (TMEP), bis(2-methacryloyloxy) ethyl phosphate (DMEP), and 2-(methacryloyloxy ethyl) phosphate (MMEP) were synthesized from phosphorous oxychloride and 2-hydroxyethyl methacrylate, which can be used as flame retardant monomers for UV-curable coating systems. The characterization of the synthesized monomers was carried out by 1H-NMR, FT-IR, thermo-gravimetric analysis, and the limited oxygen index (LOI) test. The thermal behavior of the cured films depended on phosphorous content and the methacrylate groups in the monomer. The UVcured films from TMEP, DMEP, and MMEP monomers showed LOIS of 28.5, 30.3, and 35.1 respectively. Also, LOI up to 25.4 was obtained for the UV-coated cotton fabrics, which presumably occur through a condensed phase mechanism as verified in the increased residue number. The higher performance of UV-coated cotton fabrics compared to PET was attributed to the facile dehydration and crosslinking of the cellulosic materials.