Prepartion And Properties Of Naphthalene-based Poly(Arylene Ether Ketone)s For Anion Exchange Membranes

In recent years, aromatic polyether ketones have achieved remarkable positionsamong other thermoplastic polymers because of their unique combination oftoughness, stiffness, thermooxidative stability, electrical performance, flameretardancy and retention of physical properties at high temperatures. So they havebeen successfully applied to many fields such as aviation, spaceflight, nuclear energy,communication, telecom, petroleum, machine manufacturing and traffic, in order torenew the old produces. But following the booming development of new science andtechnology revolution in world, the high performance materials have been requiredextensively and urgently. In order to improve the performances, such as optical,electrical, magnetic, introduction of functional groups onto the main chain or the sidechain have been attempted. The major research goal is to change the molecularstructure without lossing of the excellent performance of the original polymer.Naphthalene rings have been introduced into polymer structures by some authorsfor they have a larger volume than benzene rings, which can enlarge the proportion ofthe rigid groups in the main chain, decrease the mobility of segments, and thereforeincrease Tgof the polymer. The novel naphthalene-containing poly（aryl ether ketone）swith different structures of the main chain or side chain were synthesized by thenucleophilic displacement condensation reaction, and the functionalized polymerswith high performance were prepared, the relationship between structure and theperformance of the naphthalene-containing poly（aryl ether ketone）s was investisatedin detail.The thesis includes three parts. Firstly, we prepared two disubstitutedmonomers[1,5-bis（3-trifluoromethyl）-2,6-dihydroxylnaphthalene（II） and 1,5-bis（3-methyl）-2,6-dihydroxylnaphthalene（IV）] and two monosubstitutedmonomers[1-（3-trifluoromethyl）-2,6-dihydroxylnaphthalene（I） and1-（3,5-ditrifluoromethyl）-2,6-dihydroxylnaphthalene（III）]. Then we synthesized twoseries of the naphthalene-containing poly（aryl ether ketone）s with differentsubstituents. The polymer has a number average molecular weight of22699⁵6300gmol-1and polydispersity index was2.33².68. Experimental results indicated that allthe polymers had elevated glass transition temperature and thermal decompositiontemperature with the introduction of naphthalene. The membranes hand tensilestrengths were in the range of62.86¹04.13MPa, tensile modulus in the range of1.50³.83GPa, and elongation at break is from4.34to10.64%. The cast membranesfrom fluorine-containing naphthalene-based poly（arylene ether ketone）s had lowerdielectric constant than non-fluorine polymer. So fluorinated side chainsnaphthalene-containing poly（arylene ether ketone）s will have a good applicationprospect with excellent comprehensive properties.Secondly, basd on the bisphenol monomer IV which was synthezised in previouschapter, naphthalene-containing poly（arylene ether ketone）s were obtained through athree-step process involving polymerization of methylated polymers, bromination andderivatization with a diquaternary-ammonium group. The hydroxide conductivities ofthe anion exchange membranes were above10^-2S cm^-1at room temperature and themembrane with an IEC=1.46mequiv. g^-1attained an ion conductivity of7.4×10^-2Scm^-1at100℃, which is higher than many reported results. The membrane series hadlow water uptake and excellent dimensional stability, even at the highest IEC values.In addition, the membranes were insoluble in organic solvent and concentratedalkaline solution for many days, even under heating, suggesting their excellentstability. The conductivity and methanol permeability of NAPAEK-Q-100has beenfar better than commercialized Morgane ADP anion exchange membrane. Thesecombined data suggest that the membranes have potential for anion exchangemembranes for fuel cells applications.Finally, based on fluorine-containing naphthalene-based poly（arylene etherketone）s and quaternized naphthalene-containing poly（arylene ether ketone）s anion exchange membranes discussed in the former two chapters, we investigated theinfluence of the fluorine atom on the naphthalene-containing poly（arylene etherketone）s anion exchange membranes. So we synthesized two series of polymer bybisphenol-AF and bisphenol A, the-CF₃-containing quaternized anion exchangemembranes （FNAPAEK-Q-Xs） and-CH₃-containing quaternized anion exchangemembranes （HNAPAEK-Q-Xs）. Comparing the performance of FNAPAEK-Q-Xs andHNAPAEK-Q-Xs, fluorine-containing quaternized naphthalene-based poly（aryleneether ketone）s anion exchange membranes have lower water absorptivity, lowermethanol permeability, better dimensional stability and alkaline stability. Sonaphthalene-containing poly（arylene ether ketone）s anion exchange membranes wasimproved performance in the present of fluorine in the mainchain.In summary, naphthalene-based poly（aryl ether ketone）s have excellentperformance. Therefore, we prepared the naphthalene-containing polymers withdifferent functionalized side chains and main chains. The relationshipbetween structure and properties was comprehensively investigatived. And the thesisproved that naphthalene-containing poly（aryl ether ketone）s had a good applicationprospect.