Study On Synthesis And Properties Of A Novel Photopolymerizable Poly Phosphinate Flame Retardant

In recent years, UV polymerization technology has received more and more attention because of the advantages of energy-saving and environmentally protection, and the UV curable materials have required good flame resistance in many application areas. Hence, the flame retardants used in UV curable materials have attracted much attention. We have synthesized a novel photopolymerizable poly phosphinate (P-NH-AC) flame retardant by carbene polymerization. The introduction of P-NH-AC into the UV-curable materials can enhance the mechanical properties and flame resistance of the materials, because of the highly regular structure of molecule and high content of phosphorus, less volatile and good stability of the P-NH-AC. The effect of the content of P-NH-AC on kinetics of photopolymerization, flame resistance, mechanical properties and microstructure of the UV-curable materials were systematically investigated. The effect of structure of P-NH-AC on the compatibility of P-NH-AC with photoactive acrylate monomers was also explored. This study would provide theoretical basis for development and application of flame retardants with excellent comprehensive performances. The main research conclusions are as follows:1. The optimal route to synthesize poly ethyl (4-acrylamidebenzyl)phosphinate (P-NH-AC) was determined as following:first, the poly ethyl (4-nitrobenzyl)phosphinate (P-NO2) was synthesized from ethyl (4-nitrobenzyl)phosphonochloridate and diazomethane by a carbine polymerization, after then P-NO2was reduced to poly ethyl (4-aminobenzyl)phosphinate (P-NH2), finally, P-NH2reacted with acryloyl chloride to obtain P-NH-AC. The structures of all products were characterized by NMR, FT-IR and GPC.2. The compatibility of poly ethyl (4-nitrobenzyl)phosphonate (P-NO2), poly ethyl (4-aminobenzyl)phosphonate (P-NH2), poly ethyl (4-acrylamidebenzyl)phosphonate (P-NH-AC) and poly ethyl (4-methoxybenzyl)phosphonate (P-OCH3) with acrylate monomers were investigated, and the results showed that poly ethyl phosphonate have good compatibility with HE A and HEA/TMPTA(5/1wt.%). The formation of intermolecular hydrogen bonds between substituent group and hydroxyl of HEA influenced the compatibility.3. The effect of content of P-NH-AC on kinetics of photopolymerization of photopolymerization systems were investigated by RT-IR. The results showed that the rate of polymerization of systems decreased with the increase of the content of P-NH-AC, and the final double bond conversion of all systems reached above95%. 4. The combustion behavior and thermal stability of the UV-cured materials with P-NH-AC were studied by limit oxygen index(LOI), thennal gravitmetric analysis (TGA) and scanning electron microscopy (SEM). The results indicated that the LOI, Tmax and char yield at high temperature of the UV-cured material increased with the increase of the content of P-NH-AC. The LOI, Tmax and char yield at800℃of UV-cured materials containing5wt.%P-NH-AC were increased to32%,440℃and7.98%respectively.5. The hardness, contact angle, water absorption and microstructure of UV-cured films with P-NH-AC were systematically investigated. The results showed that with the increase of the content of P-NH-AC, the hardness and contact angle of UV-cured film increased, and the water absorption and dispersion surface energy decreased.