Preparation And Properties Study Of High-performance Silicon-containing Emulsifier-free Emulsion For DMFC Applications

In this thesis,the colloidal nanosilica particles(SiO2) was firstly preparated by sol-gel method, and then a series of silicon-containing core-shell structured polyacrylate/2-acrylamido-2-methyl-1-propanesulfonic acid(SiO2-CS-PA/A) nanocomposite latex particles were synthesized by the emulsifier-free emulsion polymerization method of acrylate monomers(butyl acrylate, methacrylic acid and methyl methacrylate) and 2-acrylamido-2-methyl-1-propanesulfonic acid(AMPS) with colloidal nanosilica particles as seed.In this paper, the structure and properties of emulsifier-free core-shell nanocomposite latex particles with different content of AMPS and SiO2 contents were studied, respectively. Meanwhile, the proton exchange membranes(PEMs) with different AMPS and SiO2 contents were also obtained and characterized to assess their possibility as proton exchange membranes(PEMs) in direct methanol fuel cells(DMFCs) proton exchange membrane for DMFC in order to do some efforts and attempts for the research of new type of PEM.Direct methanol fuel cells(DMFCs) are promising power sources for vehicular transportation and other applications requiring clean, quiet and portable power. The PEM is one of the most important components in DMFC and has received a great deal of attention of researchers. Currently, the PEM materials used in DMFCs are mainly perfluorosulfonic acid membranes, partially fluorinated sulfonated membranes, fluoride-free sulfonated membranes and modified membranes. Especially, organic-inorganic composites have attracted more and more researchers’ attention because they combine in a single solid both the excellent properties of organic and inorganic materials. In this thesis,our goal is to synthesize the potentially economical, environmentally friendly organic-inorganic composites with high performance for DMFC applications.The main contents of this study are as following:(1) A series of silicon-containing core-shell structured polyacrylate/2-acrylamido-2-methyl-1-propanesulfonic acid nanocomposite latex particles(SiO2-CS-PA/A) with different AMPS content were prepared by the emulsifier-free emulsion polymerization. The structures.and properties of SiO2-CS-PA/A were characterized by infrared analysis(FTIR), particle size distribution, thermal gravimetric analysis(TGA), water uptake, methanol uptake, transmission electron microscopy(TEM), methanol diffusion coefficient, proton conductivity et al.(2) A series of silicon-containing core-shell structured polyacrylate/2-acrylamido-2-methyl-1-propanesulfonic acid nanocomposite latex particles(CS-PA/A-SiO2) with different SiO2 content were prepared by the emulsifier-free emulsion polymerization. The effects of SiO2 content on the performance of membranes were studied and discussed in detail by means of various methods.The results revealed that the silicon-containing core-shell structured polyacrylate/2-acrylamido-2-methyl-1-propanesulfonic acid nanocomposite membranes showed good thermal stability, low methanol diffusion coefficient and high selectivity. These results suggested that the nanocomposite membranes were particularly promising to be used as proton exchange membranes in DMFCs.