Synthesis And Characterizations Of Novel Phosphorous Nitrogen Containing Poly(ether Sulfone)s

A new class of phosphorus-containing and nitrogen-containing monomers were utilized for the synthesis of novel phosphoruse-nitrogen synergism aromatic poly(ether sulfone)s. The new method of recrystallization can obtained a more pure and good yield. The monomer phosphorus-containing and nitrogen-containing behaves like a bisphenol when reacted with activated aryl halides. Two novel series of high molecular weight phosphorusenitrogen synergism aromatic poly(ether sulfone)s can bereadily synthesized by polymerization of phosphorus-containing and nitrogen-containing monomer with different activated dihaloaromatic compounds in NMP in the presence of potassium carbonate. The poly(ether sulfone)s possessed high glass transition temperature (Tg) and excellent thermostabilities due to the rigid heterocyclic and phosphorus-containing aromatic structure. The poly(ether sulfone)s containing different P/N molar ratio were all soluble in polar aprotic solvents like NMP, N,N-dimethylacetamide (DMAc) and Dimethylsulfoxide (DMSO), and also soluble in less polar solvents like chloroform. The good solubility can be explained by the presence of bulk pendent DOPO moieties and twist structure of DHPZ, which create a weak packing of the chains. The diffusion of solvent molecules is facilitated.Transparent and flexible films were easily prepared from all the polymers through casting from CHCl3 solutions. As expected, high molecular weight polymers were already synthesized by the polymerization of DHPZ and DOPO-PhOH or DOPO-BQ involving different molar ratio.Due to the more active OH and NH groups in DHPZ monomer than OH in DOPO-PhOH and DOPO-BQ, the molecular weights of the polymers were increased with the increasing of DHPZ unit.The structural investigation confirmed the formation of the novel phosphorusenitrogen synergism aromatic poly(ether sulfone)s as evidenced by GPC measurements, Fourier transform infrared spectra (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 31P NMR). The investigation of thermal properties confirmed the formation of the polymers as evidenced by DSC and TGA measurements. The influence of monomer ratio on their thermal stability was also investigated by adjusting the proportion of DOPO-PhOH/DHPZ and DOPO-BQ/DHPZ (mol/mol) from 80/20 to 20/80. The tests indicated that the polymers showed good thermal stability: The Tg of the polymers using phosphorus-containing (DOPO-BQ) ranged from 236℃to 273℃. Under nitrogen atmosphere, the extension starting degradation temperature of the polymers were all above 420℃, the temperature for 50% weight loss ranged from 649℃to 885℃, the Char yield at 970℃ranged from 38.1wt% to 46.6wt%. The Tg of the polymers using phosphorus-containing (DOPO-PhOH ) ranged from 206℃to 276℃. Under nitrogen atmosphere, the extension starting degradation temperatureof the polymers were all above 420℃, the temperature for 50% weight loss ranged from 785℃to 971℃, the Char yield at 1000℃ranged from 42wt% to 56wt%. Especially,the char yield of polymer PES46 was over 30wt% higher than that of the non -nitrogen PES-P at 800℃and still remained 4.4wt% at 1000℃under air atmosphere.It might be contributed to the loss of nitrogen in the polymer chain and the synergistic effect of P and N. The gases released by heating nitrogen-containing monomer and phosphorus -containing compounds form a spumose protecilve foil on the surface of the polymer. It plays a part in insulating thermal and inhibiting smoke and decrease the degradation rate of the polymer. Meanwhile, the phosphorus existing in the system obviously promotes carbonization, and it displays good retardant effectiveness in both condensed phases and gas phase. Nitrogen and phosphorus have a good synergistic effect in the polymer, which impove thermal stability and char yield efficiently. So the obtained polymer can serve as flame retardant agent in high polymer material.