聚[(四氟丙氧基)_(2-x)(三氟乙氧基)_x]膦腈合成和气体分离性能研究

SYNTHESIS OF POLY[(TETRAFLUOROPROPOXY)_(2-x)(TRIFLUOROETHOXY)_x] PHOSPHAZENES AND THEIR GAS PERMEATION CHARACTERIZATION

以六氯环三聚磷腈为原料通过真空热开环聚合制得线型聚二氯磷腈(PDCP),再通过对PDCP进行亲核取代合成制备了新的聚膦腈类高分子——聚[(四氟丙氧基)2-x(三氟乙氧基)x]膦腈,聚合物经过四氢呋喃-苯反复溶解-沉淀得到纯化产物.通过31P-NMR、1H-NMR和FTIR对其结构进行了表征;DSC法测定其玻璃化转变温度Tg;,GPC测定了分子量,XRD测定其结晶度,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.测试结果表明,得到x值分别为1.53、1.86、1.75和0的4种聚[(四氟丙氧基)2-x(三氟乙氧基)x]膦腈;其玻璃化温度Tg为-45.2℃、-45.2℃、-50.3℃和-32.3℃;重均分子量为1.2×105、5.6×105、2.6×105和6.0×105;两种取代基比例适中时显示出较高的气体透过性能,取代比例x为1.53的聚合物PH2=55 barrer,PCO2=75 barrer,PHe=40 barrer,PO2=15 barrer,H2/N2选择系数达到11.7,在合成NH3尾气中回收H2存在发展前景;O2/N2的选择系数达3.1,是一种很有希望的富氧材料.

Poly[（tetrafluoropropoxy）2-x（trifluoroethoxy）x ]phosphazenes of different substituent ratio were synthesized via nucleophilic substitution of polydichlorophosphazene（PDCP） which was prepared by vacuum thermal ring-opening polymerization of hexachlorocyclotriphosphazene（HCCP）.The final substituted polyphosphazene products were purified through the THF-benzene precipitation.31 P-NMR was used to assure the purification.The polymer structure was characterized by 1H-NMR and FTIR.The glass transition temperature was detected by differential scanning calorimetry（DSC）.The molecular weight was determined by gel permeation chromatography（GPC） and the crystallinity was tested through X-ray diffraction（XRD）.Gas permeability coefficient of N2,O2,CH4,CO2,He and H2 in these polymers at 20℃ were measured by permeate gas pressure method.The results shown that four different poly [（tetrafluoropropoxy）2-x（trifluoroethoxy） x ] phosphazene products with different x-value of 1.53,1.86,1.75 and 0 were prepared respectively.The glass transition temperature of these polymers were-45.2℃,-45.2℃,-50.3℃ and-32.3℃,and the weight-average molecular weight were 1.2 × 105,5.6 × 105,2.6 × 105 and 6.0 × 105 respectively.Polymer with substituted ratio x = 1.53 showed higher gas permeability.Its permeability coefficient of H2,CO2,He and O2 were 55 barrer,75 barrer,40 barrer and 15 barrer respectively.The selectivity coefficient of H2/N2 was 11.7,which showed potentiality in ammonia synthesized industry.In addition,the selectivity coefficient of O2/N2 was 3.1,demonstrated a promising oxygen-enriching material.