Synthesis and properties of fluorine-containing polybenzimidazole/sulfonated silica nanocomposites for high-temperature proton exchange membrane fuel cells

• Main Authors: Yen-Hsin Liu, 劉雁欣
• Other Authors: Steve Lien-Chung Hsu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/71726694826895157790

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 97 === An amorphous, fluorine-hydroxy containing polybenzimidazole (PBI) copolymer was synthesized from 3,3’-diaminobenzidine, 2,2-bis(4-carboxyphenyl) hexafluoropropane and 5-hydroxyisophthalic acid. The structures of the PBI copolymer was characterized by FTIR, XRD and 1H-NMR. PBI/SiO2 nanocomposite membranes were prepared via sol-gel process from the fluorine-hydroxy containing PBI copolymer with phenethyl trimethoxysilane (PETMS) precursor and a bonding agent. The introduction of the bonding agent results in the improvement of interfacial interaction between PBI chains and silica nanoparticles. Transmission electron microscopy (TEM) analyses showed that the silica particles were well dispersed in the PBI matrix on nanometer scale. The mechanical properties and the methanol barrier ability of the PBI/SiO2 films were improved by the addition of silica. The conductivities of the acid-doped PBI/SiO2 nanocomposites were slightly lower than the acid-doped pure PBI. Sulfonated silica (SiO2-SO3H) was prepared via sulfonation reaction between PETMS and chlorlsulfonic acid. PBI/SiO2-SO3H nanocomposite membranes were prepared via sol-gel process from the fluorine-hydroxy containing PBI copolymer with sulfonated PETMS and the bonding agent. The conductivities of the acid-doped PBI/SiO2-SO3H nanocomposites were higher than the acid-doped pure PBI and PBI/SiO2 due to the addition of sulfonated silica. However, the addition of sulfonated silica increased the methanol permeability of PBI/SiO2-SO3H films.