Synthesis and characteristics of phosphonate-containing maleimide polymers

Phosphonate-containing N-phenyl maleimide monomers were synthesized by a tw o-step reaction. All maleimide polymers were synthesized by free radical po lymerization in toluene solution using azobis(isobutyronitrile) (AIBN) as i nitiator. The structures of the maleimide monomers were identified by H-1, C-13, P-31-NMR, and element analysis. Differential scanning calorimetry (DS C) and thermogravimetric analysis (TG) were used to analyze the thermal pro perties of the polymers. The degree of polymerization in phosphonate-contai ning maleimide polymers should be affected by side chains. The introduction of phosphonate into a side chain of maleimide polymer may reduce the glass transition temperature (T-g) and thermal stability, but increase char yiel d of solid residue as an excellent flame retardant. T-g and thermal stabili ty of the phosphonate-containing maleimide polymers depended on substitutio n of the phenyl ring in the side chain. Phosphonate-containing maleimide po lymers with halogen or sulfur atom may combine the flame retarding mechanis m of gas-phase and solid-phase to promote their flame retardancy.