Study On Controlable Preparation Of Sunfonated Poly(Arylene Ether Sulfone) With Post-sulfonation And Their Properties For Proton Exchange Membranes

Proton exchange membrane fuel cells（PEMFC）can directly convert chemical energy into electrical energy,which is considered to be the most promising to become one of the future clean energy devices.Proton exchange membrane（PEM）is one of the core components of proton exchange membrane fuel cell,which has been extensively studied.In this paper,structure design of poly（arylene ether sulfone）and sulfonation method were studied,two series of sulfonated poly（arylene ether sulfone）s proton exchange membranes:random and block sulfonated poly（arylene ether sulfone）s proton exchange membranes were prepared and its various properties were characterized.In this paper,the model compound was prepared firstly,and then basing on the localization of the model compound,taking DFDPS,SDP and SDP as raw material,and DMAc as solvent to prepare poly（arylene ether sulfone）s to carry out nucleophilic substitution reaction,which can be sulfonated at specific sites.The sulfonated poly（arylene ether sulfone）s with controllable sulfonation and sulfonation sites was obtained by post-sulfonation.The random sulfonated poly（arylene ether sulfone）proton exchange membrane was prepared by membrane casting method.The intrinsic viscosity,actual ion exchange capacity（IEC）,water absorption and dimensional change rate,proton conductivity and mechanical properties were studied.On the basis of these,the block sulfonated poly（arylene ether sulfone）s with different length of the segment and different IEC was prepared,which is expected to further optimize and enhance the performance of water absorption and dimensional change rate,proton conductivity and mechanical properties.The structure of the sulfonated poly（arylene ether sulfone）was confirmed by FT-IR and ¹HNMR spectra.It was confirmed that the sulfonic acid group was successfully attached to the ortho position of the oxy ether group on the biphenyl structure,indicating that the sulfonation method could control the sulfonated polymer.The intrinsic viscosity of the polymer was characterized by an ubbelohde viscometer.The value of the intrinsic viscosity are more than 1dL/g,indicating that we successfully prepared a higher molecular weight sulfonated poly（arylene ether sulfone）,and for the poly（arylene ether sulfone）with similar molecular weight,with the increase of the IEC value,the relative viscosity of sulfonated poly（arylene ether sulfone）is larger.The sulfonation degree of sulfonated poly（arylene ether sulfone）was characterized by acid-base titration.The experimental titration of IEC is basically 93%of the theoretical value.The water absorption and proton conductivity of the membrane increased with the increase of sulfonic acid group content（IEC）and temperature,the dimensional change rate of the proton exchange membrane also increased gradually,but at IEC less than 1.60 meq·g^-1,it can maintain the integrity of the shape and the size change in the film thickness direction is larger than that in the film plane,which shows that the proton exchange membrane has anisotropy at the dimensional change rate.The thermo gravimetric analysis（TGA）shows that the proton exchange membrane began to degrade at high temperature of 325℃,which indicated that the prepared proton exchange membrane had good thermal stability.The mechanical properties test showed that the proton exchange membrane of sulfonated poly（arylene ether sulfone）has a large rigidity and is not easily deformed.At 20℃and 20%RH,the maximum tensile strength of the membrane is more than 40MPa,and the elongation at break is More than 10%.In summary,after optimization of polymer structure and sulfonation conditions,the post-sulfonation process can successfully produce poly（arylene ether sulfone）with a strictly reproducible and controlled sulfonation degree in a simple and mature process and it has a high overall performance for PEM.The proton exchange membrane prepared by block modification shows more excellent water absorption and proton conductivity than the random type,and also shows better mechanical stability.And as the length of the segment increases,these properties become more excellent.