Study On Sulfonated Poly(Phthalazinone Ether Ketone)s As Proton Exchange Membranes

In this thesis,several kinds of sulfonated poly(phthalazinone ether ketone)s containing several pendant groups have been synthesized based on the molecular design principle under the background of the application of sulfonated poly(arylene ether ketone)s in proton exchange membrane fuel cells(PEMFC).3,3'-disulfonate-4,4'-difluorobenzophenone(SDFB) is prepared by sulfonation of 4,4'-difluorobenzophenone(DFB) with fuming sulfuric acid containing 25%SO₃.Novel sulfonated poly(phthalazinone ether ketone)(SPPEK-DM) and sulfonated poly(phthalazinone ether sulfone ketone)(SPPESK-DM) containing dimethyl groups with different sulfonation degree and high molecular weight are prepared by aromatic nuleophilic polycondensation of 4-(3,5-dimethyl-4-hydroxyphenyl)-2,3-phthalazinone(DMDHPZ),SDFB, DFB or 4,4'-dichlorodiphenylsulfone(DCS),the inherent viscosity of copolymers is above 1.0dL/g.Sulfonated poly(phthalazinone ether ketone) containing phenyl groups copolymers (SPPEK-O) are synthesized via direct polycondensation from SDFB,DFB and DHPZ-O. Sulfonated poly(phthalazinone ether nitrile ketone)(SPPENK-O) containing phenyl groups with different sulfonation degree are obtained by direct nucleophilic polycondensation of SDFB,DFB,DHPZ-O and 2,6-difluorobenzonitrile(DFBN).FT-IR and ¹H-NMR are used to characterize the structure of SPPEKs.TGA is used to study the thermal properties of these polymers,the 5%weight loss temperature of these polymers is above 430℃(in sodium form) and above 318℃(in acid form) respectively,indicating they have good thermal stabilities.Sulfonated poly(phthalazinone ether ketone)s have excellent solubilities,and they can dissolve in polar aprotic solvent such as NMP and DMAC.SPPEKs films were obtained by solution casting method with N-methylpyrrolidone.The properties of these membranes have been studied in detail,which include water uptake,swelling ratio,ion exchange capacity(IEC), oxidative stability,tensile test,proton conductivities and methanol permeabilities.The results indicated that water uptake,swelling ratio,IEC,methanol diffusion and proton conductivities increased with the increasing of DS,oxidative stability decreased with DS increasing.The obtained membranes have excellent mechanical properties,the tensile test results show that tensile stress is above 47Mpa. Polymers with different structures have different performances.Compared with other polymers,the SPPEK-DM membranes have the best oxidative stabilities,probably due to the introduction of dimethyl groups which substitute the active hydrogen atoms at the ortho position of phenolate oxygen atom.Compared with other polymers,SPPENK-O membrane with a same SD has a much higher water uptake and proton conductivities.When temperature is above 85℃,all polymers with DS more than 0.9 show good proton eonductivities(＞10^-2 S·cm^-1),which meets the requirement in PEMFC application.