Study On Sulfonated Poly (Phthalazinone Ether Nitrile Ketone) Containing Pendant Phenyl Group As Membrane Materials

Proton exchange membrane fuel cells are widely used in transportation,aerospace,military power,micro power stations and other fields due to their advantages of low operating temperature,clean energy,small footprint,and long service life.However,with the expansion of application fields,the shortcomings of traditional perfluorosulfonic acid membranes have become increasingly obvious,such as high cost and low operating temperature.Sulfonated aromatic polymers as a new generation of proton exchange membrane materials,have lower cost,the structure of the rigid aromatic ring can give the membrane materials good chemical stability,thermal stability,and mechanical strength.Therefore,through the molecular structure design,the sulfonated aromatic polymer membranes are expected to replace traditional perfluorosulfonic acid membranes and become a new generation of proton exchange membranes.In this research,based on the application of sulfonated aromatic polymers containing pendant group in proton exchange membranes,from the perspective of molecular structure design,poly（phthalazinone ether nitrile ketone）containing pendant phenyl group（PPENK-P）,and sulfonated poly（phthalazinone ether nitrile ketone）containing pendant phenyl group（SPPENK-P）were designed and synthesized,SPPENK-P proton exchange membranes were prepared by solution casting method,the membranes performance were tested to explore the influence of the different monomer ratios of polymer to the membrane performance after the membrane formation.The main research results are as follows:（1）PPENK-P with different monomers proportioning were synthesized via high temperature polycondensation from 4-（4-hydroxyphenyl）-2,3-phthalazin-1-ketone（DHPZ）,4-（3-phenyl-4-hydroxyphenyl）-2,3-phthalazinone-1-ketone（DHPZ-P）,2,6-dichlorobenzonitrile,4,4′-difluorobenzophenone.Their structure were characterized by FT-IR and 1H-NMR,solubility,intrinsic viscosity,and thermal stability were tested.The results show that PPENK-P can be dissolved in common solvents,intrinsic viscosity all above 0.99 d L/g,thermal weight loss of 5%are above 470℃,and the comprehensive performance are good.（2）PPENK-P were sulfonated through the direct sulfonation method,using concentrated sulfuric acid as the sulfonating agent.The effect of the reaction time on the degree of sulfonation was first explored,to optimize the reaction conditions and determine the reaction time.Afterwards,using the same experimental procedure to prepare a series of SPPENK-P.According to the IEC values from different samples,8 h is finally selected as the time of the sulfonation reaction.The IEC test results show that the IEC values of SPPENK-P are between0.99 and 1.55 mmol g^-1,increasing with the ratios of-P monomer increase.SPPENK-P can be dissolved in DMAC,DMSO,DMF,intrinsic viscosity all above 1.60 d L/g,5%thermal weight loss temperature are between 350 and 410℃,proved SPPENK-P have good thermal stability.（3）A series of SPPENK-P proton exchange membranes were prepared by the solution casting method using NMP as the solvent,and the membrane performance are tested.The test result show that as the proportion of DHPZ-P moiety in SPPENK-P increase,the IEC value,water absorption,swelling rate,and proton conductivity of the membranes increase,while the oxidation resistance decrease.The water uptake of SPPENK-P membranes at 25℃are above8%,the maximum swelling rate is 9.0%×3.6%,and the oxidation resistance are all above 17h and the proton conductivity at 95℃can reach 9.59×10^-2 S/cm.