New Phosphonated Methacrylates: Synthesis, Photocuring and Study of their Thermal and Flame‐Retardant Properties

In this work, a new methacrylate phosphonate monomer synthesis was described according to two routes: firstly, by condensation of methacrylic acid with a phosphonate epoxide and secondly by an esterification between methacryloyl chloride and a phosphonate diol. The photoinduced polymerization of this new monomer was studied as a function of reaction temperature. The optimal conversion of the photopolymerization was 81% for temperatures below 60 °C. Above 60 °C, the existence of a thermal polymerization leads to a decrease in the apparent photochemical yield. This new monomer is less reactive than the commercial dimethacrylate polyether of Bisphenol A we have used for copolymerization. Mechanical and thermal properties of the final copolymers were studied as a function of methacrylate phosphonate monomer content. T g of the copolymers reaches a maximum when the phosphorus content is about 2%. The addition of phosphorus leads to an improvement of the thermal and flame‐retardant properties. Thus, addition of 2% phosphorus allows us to decrease the degradation rate, to increase the amount of remaining residue after combustion up to 12%, and finally to increase the Limiting Oxygen Index (LOI) from 16.8 (0% P) to 21.4 (2% P).Synthetic routes to methacrylate phosphonated monomer.