Synthesis And Characterization Of Poly (2-acrylamide-2methyl Propane Sulfonic Acid Brush And Pt Complexes

Proton exchange membrane fuel cell (PEMFC) is a device which can convertelectrochemical energy into electrical energy directly by the reaction of hydrogen fueland oxygen. Because of its remarkable advantages, including high energy conversionefficiency, no noise, rapid start up and zero emission，PEMFC is considered to be anideal alternative power sources for mobile power supply and backup power in thefuture.Catalyst is the core material of the proton exchange membrane fuel cell.Pt-based catalysts are the commonly used catalysts in proton exchange membranefuel cell (PEMFC). However, the traditional Pt/C catalyst of PEMFC are subjected tostrongly oxidizing conditions, high water content, low acidic environment, highvoltage, high oxygen content, and high temperature (50-90℃) and can be thereforeoxidized and corroded easily. The insufficient stability of the Pt/C catalysts togetherwith the high Pt-loading in the electrode remains major obstacle to the widespreadcommercialization of PEMFCs. In this thesis, mainly research contents include thepreparation of Nafion impregnated with SiO2as membrane electrolyte, andpreparation of surface attached polymer brush on membrane through free radicalpolymerization of2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS) ascatalyst support. With the ordered structure of polyanion brushes, cationic polymerstabilized Pt nanoparticles can be therefore deposited on the surface throughelectrostatic interactions. The main results and conclusion of this thesis are summarizedas following:1）Composite membranes containing Nafion and SiO2nanoparticles can besuccessfully synthesized by the four ethyl orthosilicate (TEOS) as the precursor andNafion resin as surfactant using the principle of electrostatic self-assembly method. With the content of SiO2of5wt%, silica nanoparticles are dispersed uniformly on thesurface of composite membrane. With the good thermal stability and certain waterretention ability, the Nafion-SiO2nanocomposites are suitable for the elevatedtemperature operations as membrane electrolyte.2)2-acrylamide-2-methyl-1-propane sulfonic acid polyelectrolyte can bepolymerized by radical polymerization with surface attached initiator moieties. Theresults show that the molecular weight is independent on reaction time unless the high viscosityinduced “cage effect” appeared. the molecular weight increase slightly when the reactiontime less than4hours.But the molecular weight increase rapidly when it reacti6h. themolecular weight is proportional to the monomer concentration when the monomerconcentration less than2.5mol/L, it increase slightly when the monomerconcentration more than3mol/L. So we chose the polymerization time is2hours,monomer concentration is2.5mol/L.3) AFM and SEM micrographs clearly show that the cationic polymer PDDA/Ptcomplexes can be uniformly adsorbed on the AMPS/Nafion/SiO2membrane throughelectrostatic interaction after soaking AMPS/Nafion/SiO2film into PDDA/Pt sol foran hour.