Molecular Design And Characterization Of Poly(Aryl Ether Ketone)s And Poly(Aryl Ether Sulfone)s Containing Naphthalene

In recent years aromatic polyether ketones and polyether sulfones have achievedremarkable positions among other thermoplastic polymers because of their uniquecombination of toughness, stiffness, thermooxidative stability, electricalperformance, flame retardancy and retention of physical properties at hightemperatures. So they have been successfully applied to many fields such as aviation,spaceflight, nuclear energy, communication, telecom, petroleum, machinemanufacturing and traffic, in order to renew the old produces. But following thebooming development of new science and technology revolution in world, the highperformance materials have been required extensive and urgent. In order to improvethe characterization of poly(aryl ether keonte)s and poly(aryl ether sulfone)s further,and fulfill the requirement of some extreme environment like the high temperatureand irradiation environment, it is made them to take place crosslinking reaction. It isthermoplastic material before process which can be molded or casted, and thenbecomes thermoset through crosslinking reaction after process, so it has both kind ofadvantage of materials. It's required to introduce crosslinking group. It can not beused the generally aliphatic crosslinking group over the polymer material because itcan decease thermal characterization of poly(aryl ether keonte)s and poly(aryl ethersulfone)s, but only to look for the material which has aromatic crosslinking group.The aim of the dissertation is from the design of molecular structure to synthesizenew monomers and then to synthesize new poly(aryl ether ketone)s and poly(arylether sulfone)s containing naphthalene with different chemical environment andlinking position through the nucleophilic displacement condensation reaction. Thepolymers are treated under different conditions. It is to be used several researchmethods to investigate the thermal crossliniking behavior, discussed the effection ofnaphthalene with different chemical environment and linking position, and made upthe mechanism of crosslinking reaction. The dissertation includes three parts: the synthesis and characteraztion ofpolymers containing diether naphthylene, diketo naphthylene and disulfonenaphthylene. We used 1,5-dihydroxynaphthalene(1,5-DHN), hydroquinone(HQ) and4,4'-Difluorobenzophenone (DFB) to synthesize the new high molecular weightglass poly(ether ether ketone)s random copolymers containing 1,5-naphthalenemoieties. The glass transition temperature (Tg) increases and the melttemperature(Tm), crystallinity decrease with increasing the content of naphthalenemoieties. The mechanical property of copolymers decreases a litter but retaines theadvantage of poly(aryl ether ketone). These results can be attributed to thedisturbance of the segmental movement and the destruction of the symmetry andregularity of the molecular chains due to the introduction of the naphthalene moiety.But we found that it's difficult to synthesize copolymers containing high content ofnaphthalene, because the activity of naphthalene is much higher than that of benzeneto take place crosslinking reaction during the polymerization. So we used anothersynthesis method which synthesizes a new difluoro oligomer1,5-bis(4-(4'-fluorobenzoyl) phenoxy) naphthalene(1,5-BFPN) with4,4'-difluorobenzophenone(DFB) and 1,5?dihydroxynaphthalene(1,5-DHN) andthen synthesizes dihydroxy-terminated PEEK oligomers with4,4'-difluorobenzophenone(DFB) and hydroquinone, finally, to synthesize thepoly(ether ether ketone) copolymers that contained regular sequences of phenyleneand naphthylene using the two kind of oligomers. It was found the characterizationof regular copolymers is similar with that of random copolymers. The thermalcrosslinking reaction was monitored by differential scanning calorimetry (DSC) andwide-angle X-ray diffraction (WAXD), when the poly(ether ether ketone)s randomcopolymers containing 1,5-naphthalene moieties were treated above 320 C under ooxidative conditions, and the crosslinking reaction accelerate following increasing thecontent of naphthalene and treated temperature. ESR results suggested that thecrosslinking reaction proceeds via free radicals. Subsequently two kinds of free radicalswere characterized: one is an RO? type free radical and the other is anaphthalene ring free radical. The measured concentration of RO? was nearlyconstant at first, and then the concentration increaseed linearly. Because theconcentration of RO? free radicals is higher than that of naphthalene ring freeradical, RO? free radicals take a predominant role in crosslinking reactions. Themethod of isothermal degradation was used to find the degradation reactionhappened when 1,5-BFPN was treated at 340 oC. We made out the mechanism ofcrosslinking reaction about the copolymers containing 1,5-naphthalene throughthe above results. We synthesized a new monomer 1,4-bis (4-fluorobenzoyl) naphthalene(1,4-BFN)using the acyl chloride reaction and Friedel-Crafts acylation reaction of1,4-Naphthalenedicarboxylic acid with fluorobenzene. Poly (aryl ether ketone)copolymers possessing various compositions of 1,4-naphthylene and 1,4-phenylenemoieties were prepared by the reaction of hydroquinone(HQ) with1,4-bis(4,4'-fluorobenzoyl) naphthalene (1,4-BFN) and 4,4'-difluorobenzophenone(DFB). The glass transition temperature and solubility increase, while the meltingtemperature decrease with increasing of 1, 4-naphthalene moieties, and themechanical of 1,4-PEEKNK is as well as that of PEEK. The samples of1,4-PEEKNK treated above 260oC were detected by DSC, and the Tg increasesfollowing increasing the treated time and temperature. The method of isothermaldegradation was used to find the degradation reaction did not happen when1,4-PEEKNK was treated at 260℃. We made out the mechanism of crosslinkingreaction about PEEKNK through the results FT-IR,NMR,ESR. Finally, we synthesized 1,5-, 2,6-and 2,7-Bis-(4-fluorosulfonyl)naphthaleneisomers with the acyl chloride reaction and Friedel-Crafts acylation reaction.Aromatic poly(aryl ether sulfone)s containing naphthylene isomers were prepared bypolycondensation of new monomers with hydroquinone orbis(4-hydroxyphenyl)sulfone. The Tg of PEESNS is similar with that of PES andPEESNS have excellent solubility and casting. The polymers containing1,5-naphthalene (a-1, a-2) took place crosslinking reaction when the samples weretreated at 300oC and the thermal stabilities of PEESNS (a-1,b-1,c-1) were assessedby thermal degradation and kinetics. The results of thermal degradation expressedthat the polymer a-1 is different with b-1 and c-1. The degradation temperature andapparent activity energy of a-1 is much lower than that of b-1 and c-1, and judgedfrom the therogravimetric curves and apparent activity energy, the degradationreactions are different at nitrogen and air. The degradation reactions can be dividedinto two parts at air environment. Concluding from above, we have synthesized three kind of new poly(aryl etherketone)s and poly(aryl ether sulfone)s containing naphthalene with different...