Flexible transparent flame-retardant membrane based on a novel UV-curable phosphorus-containing acrylate

A novel phosphorus-containing acrylate monomer (AOPA) was synthesized starting from 2-methy-2,5-dioxo-1,2-oxaphospholane and hydroxyethyl acrylate. The structure of AOPA was characterized with FTIR and H-1 NMR. AOPA shows good compatibility with polyethylene glycol diacrylate (PEGDA) and can polymerize with PEGDA under UV light irradiation at different mass ratios to form membranes with high transparency (above 88.9% of light transmittance in the range of 400-800 nm) and flexibility. Incorporating 20 wt% of AOPA in PEGDA reduced the total heat release and peak rate by 50.3% and 38.4%, respectively, as measured by micro combustion calorimeter. The membrane containing 40 wt% of AOPA with 0.4 mm thickness can pass the UL94 V0 rating, and limiting oxygen index reaches 33.4%. TG-FTIR and SEM-EDX analysis show that the presence of AOPA depresses the thermal degradation and promotes the char formation.