聚[(六氟异丙氧基)_(2-x)(三氟乙氧基)_x]磷腈合成和气体分离性能研究

SYNTHESIS AND GAS PERMEATION CHARACTERIZATION OF POLY[(HEXAFLUOROISOPROPYLOXY)_(2-x)(TRIFLUOROETHOXY)_x]-PHOSPHAZENE

合成制备了聚磷腈类高分子——聚[(六氟异丙氧基)2-x(三氟乙氧基)x]磷腈,并通过NMR、FTIR、XRD、GPC、DSC等测试手段对聚合物进行了结构表征和性能测试,通过压力法透气性能测定仪测定了聚合物膜对N2、O2、CH4、CO2、He、H2等气体的透过性能.结果表明,三氟乙氧基的竞争取代能力较六氟异丙氧基稍强;得到x值分别为1.64、1.72和1.81的3种聚合物;其玻璃化温度Tg为-20.21℃、-42.83℃和-43.41℃;重均分子量为5.06×105、1.49×105和2.69×105;两种取代基比例适中时显示出较高的气体透过性能,渗透系数PN2=20barrer,PCO2=124barrer,PHe=85barrer;CO2/CH4和He/CH4的选择系数达到11.5和4.8,在天然气的净化和回收He中显示了潜力;H2/N2的选择系数达到6,而PH2=43barrer,在合成NH3尾气中回收H2存在发展前景。

Poly[（hexafluoroisopropyloxy）2-x（trifluoroethoxy）x]phosphazene with different substituent ratios was synthesized.The final substituted polyphosphazene products were purified through the THF-benzene precipitation to remove impurity.31P-NMR was used to assure the purification.The structure of this polymer was characterized by 1H-NMR,FTIR,XRD,GPC and DSC.Gas permeability coefficients of N2,O2,CH4,CO2,He,H2 in these polymers at 20℃ were measured by the permeate gas pressure method.The trifloroethoxy group showed more competitive substitution than hexafluoroisopropyloxy under same nucleophilic substituted reaction condition.The x-value of three different poly [（hexafluoroisopropyloxy）2-x（trifluoroethoxy） x ]phosphazene products were 1.64,1.72 and 1.81 respectively.The glass transition temperature of these polymers were-20.21℃,-42.83℃ and-43.41℃,and the weight-average molecular weight were 5.07 × 10^5,1.49 × 10^5 and 2.69 × 10^5,respectively.These polymers showed higher gas permeability.Its permeability coefficient of N2,CO2 and He were 20 barrer,124 barrer and 85 barrer respectively,and the selectivity coefficient of CO2 /CH4 and He /CH4 were 11.5 and 4.8,which showed great potentiality to be applied in natural gas industry.In addition,the selectivity coefficient of H2 /N2 was 5.8,the permeability coefficient of H2 was 43 barrer,which also showed special potentiality in ammonia synthesis industry.