The Preparation And Modification Of SPEEK Proton Exchange Membrane

The sulfonated polyetheretherketone(SPEEK)is an ideal matrix for proton exchange membranes(PEM).The excellent mechanical strength of SPEEK is provided by rigid hydrophobic main chain,and it's endowed with the proton conductivity by hydrophilic sulfonic acid groups on the side chain.The structure of relatively narrow hydrophilic-hydrophobic phase separation can effectively inhibit penetration of methanol fuel.However,the proton conductivity of SPEEK mainly depends on the degree of sulfonation.The proton conductivity increases with the degree of sulfonation,at the same time,which leads to a decrease in mechanical strength,dimensional stability,and resisitance of methanol.In this paper,SPEEK with a higher degree of sulfonation is used as the PEM matrix.Its excessive water-absorption and swelling at high temperature leads to a sharp decline in mechanical properties.For this defect,the polyetheretherketone nanofibers(PEEKNF)prepared by core-shell electrospinning are penetrating into the SPEEK matrix by dipping to maintain a complete nanofiber network,which effectively improves the dimensional stability and mechanical strength of the PEEKNF/SPEEK composite membrane.On this basis,the interaction between the various components of the composite membrane and its impact on performance were studied by FTIR,SEM,proton conductivity,dimensional stability,water absorption,and tensile testing.However,the inert hydrophobic molecular chain composed of alternating benzene rings and ether bonds in PEEKNF dilutes the concentration of sulfonic acid groups,reduces the migration sites of protons,and causes the proton conductivity of the composite membrane to decrease.If the hydrophilic functionalization modification of PEEKNF will reduce its mechanical strength,for that reason,the hydrophilicity of NaA molecular sieve is used to improve the conductivity of PEEKNF/SPEEK composite membrane,Two different methods,hydrothermal-in-situ growth and mechanical blending,are used to dope with NaA zeolite.Using the porous adsorption and multiOH property of NaA to further improve the conductivity of PEEKNF/SPEEK composite membrane.Under the conditions of same component,the NaA in NaA/SPEEK/PEEKNF composite membrane prepared by the blending method is dispersed more uniformly,and electrical conductivity is higher than the NaA@PEEKNF/SPEEK composite membrane prepared by the in-situ growth method.At 60 ?,1%NaA/SPEEK/PEEKNF composite membrane has the highest conductivity,because excessive content of NaA will cause agglomeration and affect the performance of the composite membrane.Compared with PEEKNF/SPEEK,the PEEKNF and SPEEK matrix in the 1%NaA/SPEEK/PEEKNF composite membrane are bonded more tightly,thus improving the proton conductivity of the composite membrane effectively while improving dimensional stability and mechanical strength.The "proton conductor",phosphotungstic acid(HPW),further improves the conductivity of the PEEKNF/SPEEK composite membrane.PEEKNF hinders the loss of HPW by limiting the water absorption and swelling of the SPEEK matrix.The zeolite adsorbs HPW called NaA@HPW is blended with SPEEK to prepare a membrane,which can further reduce the loss of HPW under high temperature conditions,and obtain a composite membrane with excellent comprehensive performance.It is a new method to make a balance between proton conductivity,dimensional stability,and mechanical strength.