Performance Of Ionic Liquid Doped ABPBI/Glycidyl POSS Star Shaped Hybrid Proton Exchange Membrane

Development of clean and sustainable energy sources has attracted much attention due to sacristy of fossil fuels and environmental pollution.Hydrogen fuel cells have been considered as one of the most important technology in 21^st century due to the high energy sources,zero emission and abundant sources.Proton exchange membrane fuel cells?PEMFCs?have been used as alternative energy sources for vehicles,stationary power suppliers,submarines and portable devices.Proton exchange membranes?PEMs?play an important role in PEMFCs since PEMs act as proton conductor,supporter for electrocatalysts and separator for reactants,which mainly determinate the fuel cell performance of PEMFC devices.Nafion membrane form DuPont is normally used in recent PEMFCs and the working temperature of PEMFC is restricted below 100 ^oC;while,high cost of Nafion membrane blocks the wide commercialization of PEMFCs.Thus,development of PEMs working under high temperature with low cost is desirable for PEMFCs.Polybenzimidazole?PBI?and its derivate receive considerable attention due to the excellent thermal stability and mechanical properties as well as high proton conductivity under non-humidified condition after doping with phosphoric acid.Poly?2,5-benzimidazole??ABPBI?,the simplest structure in PBI families,was selected as matrix in this thesis and[BMIM]BF₄ was filled into the ABPBI matrix as proton conductor.Meanwhile,Glycidyl POSS?EP-POSS?was utilized as inorganic fillers in order to promote the thermal stability and mechanical properties of the hybrid membrane.The main research items in this thesis were described as follow:1.ABPBI/EP-POSSS hybrid membrane was synthesised by the monomers obtained from the ring-open reaction between DABA and EP-POSS.SEM results suggested that EP-POSS was uniformly dispersed in the ABPBI matrix.TGA tests showed the film has good thermal stability under 300 ^oC.When EP-POSS content is 2%,the contact Angle is 64.34°,the water uptake level is 20%,double of the pristine membrane.The proton conductivity of phosphate doped composite membrane is 0.02S/cm at 90 ^oC.2.The hybrid membrane was fabricated from the as-synthesized ABPBI and ionic liquid?IL?via solution casting.The structure,thermal stability,surface morphology and proton conductivity of the hybrid membrane were systematically studied by FT-IR,TGA and SEM,respectively.The results indicated that the thermal stability of the composite film decreased slightly with the introduction of ionic liquid,but it remained good thermal stability within 300 ^oC.Water adsorption were simultaneously increased up to 23%with the increment in IL content;The proton conductivity of composite membrane is 0.01 S/cm at 90 ^oC.3.ABPBI/EP-POSS hybrid membrane was doped with ionic liquid to form ABPBI-EPOSS/IL hybrid membrane.Lower thermal stability was found after doping with IL revealed by TGA measurement.The water adsorption as well as proton conductivity was improved due to the presence of IL,which was reached 7.18×10^-3S/cm tested at 90 ^oC.