A double-click strategy for the synthesis of P and N-containing hydrolytically stable reactive flame retardant for photocurable networks

The use of modern chemical routes and the development of innovative material designs bring smart solutions to the problems in materials science and open up new horizons for future research. In this work, we utilized from two click reactions to prepare a P and N-containing reactive flame retardant. The para-fluoro groups of bis(pentafluorophenyl)phenyl phosphine oxide were converted to azides and then the obtained compound was reacted with propargyl acrylate via copper-catalyzed azide-alkyne cycloaddition reaction. The effect of the synthesized monomer (10%, 20%, and 30%) on the mechanical, thermal, and flame retardancy properties of an aliphatic polyurethane acrylate was investigated. The newly synthesized monomer led to a slight decrease in double bond conversion percentages, an increase in tensile strength of the photocured samples, and a decrease in the elongation at break values. The glass transition temperatures increased with the increasing amount of the flame retardant monomer as well as the limiting oxygen index (LOI) values. When the flame retardant ratio was 30% in the formulations, almost a 25% enhancement was realized in the LOI values.