Preparation, characterization and flame retardancy of phosphorus-containing poly-styrene-acrylate emulsion

Phosphorus (P)-containing monomer (P-monomer) was firstly prepared by condensation reaction between 2-hydroxyethyl methacrylate and phosphorus pentoxide (P(2)O(5)) and then used to prepare P-containing poly-styrene-acrylate (P-PSA) emulsion by semi-continuous emulsion polymerization. The components of the prepared P-monomer were characterized by potentiometric titration method. The chemical composition of the P-PSA co-polymer was studied by Fourier-transform infrared spectra. The storage stability properties of P-PSA emulsion were tested by Ca(2+), centrifugal and mechanical stability tests. The thermal stability and flame retardancy of the P-PSA co-polymer were studied by thermogravimetric analysis, limiting oxygen index and UL-94 method. The results show that stable P-PSA emulsions can be successfully prepared, and the latex particles present a spherical structure. When the P-monomer content is 30 wt%, the P-PSA co-polymer can pass the UL-94 test (V0 level) and the char yield is 54 wt% at 700°C. Scanning electron microscopy results indicate that incorporation of the P-monomer shows a condensed-phase flame-retardant effect. This study provides useful suggestions for the application of the flame-retardant P-PSA emulsion in the coating industry.