Study On Sulfonated Poly(Phthalazinone Ether Ketone Ketone)s Containing Pendant Phenyl Groups As Membrane Materials

In recent years, faced with the increasingly serious problems on energy, resources and evironment, countries around the world have enhanced the research and development of renewable energy technology. As one of the key materials in the field of new energy, ion exchange membranes are mainly used in fuel cells and different types of flow batteries. The former is mainly used for electric vehicle power source, the latter is mainly used for large-capacity storage.Poly(phthalazinone ether ketone ketone)(PPEKK) is a kind of novel materials with good solubility, high mechanical strength, well membrane-forming, high thermal stability and good chemical stability. Compared with commercial Nafion membranes, PPEKK has lower cost. In this thesis, sulfonated poly(phthalazinone ether ketone ketone)s (SPPEKKs) containing side chains with different sulfonation degrees have been synthesized based on the molecular design principle under the background of the application of sulfonated poly(arylene ether ketone ketone)s in proton exchange membrane fuel cells(PEMFC) and vanadium redox flow battery(VRB). The correlative performances of all polymers are studied.Poly(phthalazinone ether ketone ketone)s containing different numbers of pedant phenyl groups(PPEKK-Ps and PPEKK-dPs) are synthesized via aromatic nucleophilic polycondensation from4-(3-phenyl-4-hydroxyphenyl)-2,3-phthalazin-l-ketone(DHPZ-oP),4-(3,5-diphenyl-4-hydroxyphenyl)-2,3-phthalazin-1-ketone(DHPZ-dP),4-(4-hydroxyphenyl)-2,3-phthalazin-1-ketone (DHPZ), and1,4-bi(4-fluorobenzoyl) benzene. The structures of the polymers are characterized by FT-IR and’H-NMR. The inherent viscosities, solubilities, thermal stabilities, mechanical properties of PPEKK-Ps and PPEKK-dPs have been measured respectively. The intrinsic viscosities of copolymers are above0.9dL/g. Td5%of PPEKK-Ps and PPEKK-dPs are higher than506℃and490℃, indicating good thermal stabilities. PPEKK-dPs also show good mechanical properties.Sulfonated poly(phthalazinone ether ketone ketone)(SPPEKK-Ps and SPPEKK-dPs) are prepared with98%concentrated sulforic acid as sulfonating agent. Chemical structures of the polymers are characterized by FT-IR and-1H-NMR. The sulfonated polymers have good thermal stabilities.SPPEKK-P and SPPEKK-dP membranes are prepared by solution casting method using N-methylpyrrolidone as solvent. The properties of the membranes have been measured in details. SPPEKK-P and SPPEKK-dP membrances have good solubilities in polar aprotic solvent such as NMP, DMAc and DMSO, the intrinsic viscosities of them are above5.0dL/g. Water uptake, swelling ratio, proton conductivities and methanol permeabilities of SPPEKK-Ps and SPPEKK-dPs increase with the increasing IEC and temperature, the membranes also exhibit good mechanical properties and oxidative stabilities. The proton conductivities of SPPEKK-P-100and SPPEKK-dP-80membranes are7.44X10’2S-cm-1and14.41X10-2S·cm-1at95℃, respectively, while the methanol permeabilities of them are5.57X10-8cm2·s-1and1.29X10-7cm2·s-1, which would meet the requirement of fuel cell application.The VO2+permeabilities, stabilities in VO2+solution, area resistances and single cell properties of SPPEKK-P membranes are studied, respectively. The result shows that SPPEKK-P membranes have good stabilities in VO2+solution and low VO2+permeabilities. The area risistances are between0.66-1.29Ω2cm2. The current efficiency of VRB single cells with SPPEKK-P membranes is higher than98.0%, the engery efficiency of cells with SPPEKK-P-100reaches87.6%, which is higher than that with Nafion117membrane(86.0%). All the properties indicate that SPPEKK-P membranes have good prospects of application in VRB.