Study On The Series Of Sulfonated Poly (Phthalazinone Ether Sulfone Ketone) Proton Exchange Membranes

Proton exchange membrane (PEM) is a key of fuel cell. Non-fluorinated PEMs, which can be prepared through sulfonation and hybridization, exhibit higher properties of water uptake, methanol resistance and environmental friendship than that of Nafion. However, there are still some problems needed to be solved, such as improving resistance of swelling, reducing lose of the electrolyte with water in hybrid membranes during the fuel cell operation. In this thesis, novel PEMs with high water uptake at ambient temperature are prepared through a heterogeneous sulfonation process of the poly (phthalazinone ether sulfone ketone) (PPESK). Further modifications of SPPESK membranes through cross-linking and interpenetrating with polyacrylic acid are performed in order to improve swelling resistance and proton conductivity of the membranes. Detail contents of this thesis are as follows:SPPESKs were synthesized through a heterogeneous sulfonation process with fuming sulfuric acid as sulfonating agent and organic reagent re-precipitation as post treatment. The heterogeneous sulfonation reaction of SPPESK is verified to first occur on the interface of the acid and the chloroform phases, and then go on in the acid phase. Based on this experimental result, we bring forward that the acid phase is the main location of the heterogeneous sulfonation reaction, which may provide instruction of this kind of sulfonation reaction. Compared with the homogenous sulfonation reaction, there is less acid consumption, shorter time usage and higher DS of water-soluble SPPESK obtained. SPPESK membranes exhibit high water uptake, nearly 2 times higher than that of Nafion with similar dimensional variation. Proton conductivity of the SPPESK membranes is comparable or higher than that of Nafion under the same testing condition.High proton conductivity of SPPESK membranes needs very high DS of SPPESK, which often leads to dissolve of the membranes at elevated temperature. Cross-linked SPPESK membranes were prepared through cross-linking (XL) of sulfonated acid groups with both aliphatic and aromatic diamine. SPPESK of high DS and suitable degree of cross-linking were used in order to neutralize the decreasing proton conductivity made by cross-linking. Proton conductivity and dimensional stability of the XL SPPESK membranes is...