Molecular Design And Characterization Of Poly(Aryl Ether Ketone)s Containing Anthracene Moieties

In recent years aromatic poly(ether ketone)s have achieved remarkable positions among other thermoplastic polymers because of their unique combination of toughness, stiffness, thermooxidative stability, electrical performance, flame retardancy and retention of physical properties at high temperature. They have been successfully applied to many fields such as aviation, spaceflight, nuclear energy, communication, telecom, petroleum, machine manufacturing and traffic, in order to renew the old produces. But following the booming development of new science and technology revolution in world, the high performance materials have been required extensive and urgent. In order to improve the characterization of poly(aryl ether keonte)s further, and fulfill the requirement of some extreme environment like the high temperature, it is made them to take place crosslinking reaction. It is thermoplastic material before process which can be molded or casted, and then becomes thermoset through crosslinking reaction after process, so that it has both kind of advantage of materials. It's required to introduce crosslinking group. It can not be used the generally aliphatic crosslinking group over the polymer material because it can decease thermal characterization of poly(aryl ether keonte)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 synthesize new monomers and then to synthesize new poly(aryl ether ketone)s containing anthracene with different linking position through the nucleophilic displacement condensation reaction. The polymers are treated under different conditions. It is to be used several research methods to investigate the thermal crossliniking behavior, the effection of anthracene with different linking position, and make up the mechanism of crosslinking reaction.The dissertation includes three parts: the synthesis and characterization of end capped polymers containing anthracene, anthracene moieties in the pendent and anthracene in the backbone.We used new end capped monomer 9-AnF, resorcin and 4,4'-difluorobenzo phenone (DFB) to synthesize the new poly(ether ether ketone)s containing 9-anthracene moieties. Several research methods were used to confirm the polymer strctures. The thermal crosslinking reaction was monitored by differential scanning calorimetry (DSC), when the poly(ether ether ketone)s polymers containing 9-anthracene moieties were treated above 300 oC under nitrogen or oxidative conditions, and the crosslinking reaction accelerates following increasing the content of anthracene and treated temperature. ESR results suggested that the crosslinking reaction proceeds via free radicals. Subsequently two kinds of free radicals were characterized: one is an AnO·type free radical and the other is a An·free radical. The measured concentration of AnO·was nearly constant at first, and then the concentration increaseed linearly. Because the concentration of AnO·free radicals is higher than that of An·free radical, AnO·free radicals take a predominant role in crosslinking reactions. The method of isothermal degradation was used to find the degradation reaction happened when PEEKn-An was treated at 300 oC. We made out the mechanism of crosslinking reaction about the end capped polymers containing 9-anthracene through the above results.A new monomer 4-(2,6-dihydroxyphenoxy)phenyl methanone-9-anthracene was synthesized in a three-step process including the Friedel-Crafts acylation reaction of anthracene and 4-fluoro-benzoyl chloride with anhydrous powdered zinc chloride as catalyst, the aromatic nucleophilic substitution from compound (9-(4-fluorobenzoyl)anthracene) and 2,6-dimethoxyphonol to yield compound (4-(2,6-dimethoxyphenoxy)phenyl methanone-9-anthracene), and the demethylation reaction of compound in the mixture hydroiodic acid and acetic acid at reflux temperature. The bisphenol was obtained with high purity and high yield, and its structure was identified by its fully assigned NMR spectra. Poly (aryl ether ketone) copolymers possessing various compositions of 4-(2,6-dihydroxyphenoxy)phenyl methanone-9- anthracene were prepared by the reaction of resorcin with 4- (2,6-dihydroxyphenoxy) phenyl methanone -9- anthracene and 4,4'- difluorobenzophenone (DFB). The glass transition temperature increases with increasing of 4-(2,6-dihydroxyphenoxy)phenyl methanone-9-anthracene moieties. The samples of S-PEEKn-An treated above 300 oC were detected by DSC, and the Tg increases following increasing the treated time and temperature. The method of isothermal degradation was used to find the degradation reaction did not happen when S-PEEKn-An was treated at 300 oC. We suggested the mechanism of crosslinking reaction about S-PEEKn-An were similar with that of the end capped polymers through the results of FT-IR, NMR,ESR.Finally, we synthesized 9,10-bis(4-fluorobenzoyl) anthracene (AnBF). isomers with the Friedel-Crafts acylation reaction. Aromatic poly(aryl ether ketone)s containing anthracene isomers were prepared by polycondensation of new monomers with hydroquinone. The Tg of PEEKAnK is higher than that of PEEK and PEEKAnK. The polymers containing 9,10-anthracene took place crosslinking reaction when the samples were treated at 300oC and the thermal stabilities of PEEKAnK were assessed by thermal degradation. When treated under the above condition, the thermal properties and crystallized behavior of PEEKAnK were influenced by crosslinking. WAXD results indicated that the crystallization of PEEKAnK was damaged through thermal treating. The results further confirmed the formation of crosslinking network, which caused by limitation of movement of polymer chain. FT-IR and ESR method were used to study the crosslinking procedure, which indicated that subsequently two kinds of free radicals were characterized: one is an AnO·type free radical and the other is a An·free radical. The measured concentration of AnO·was nearly constant at first, and then the concentration increased linearly. Because the concentration of AnO·free radicals is higher than that of An·free radical, AnO·free radicals take a predominant role in crosslinking reactions. At 260oC and 300oC, the concentration of the free radicals increased slowly, which mainly lead to crosslinking; while at 340oC the concentration of the free radicals increased extremely largely, indicated that at 340oC the excess of free radicals would play a bad role of the polymer for further use.Concluding from above, we have synthesized three kind of new poly(aryl ether ketone)s containing anthracene with different linking position through the nucleophilic displacement condensation reaction, and their basic properties were studied. We find all of them can take place crosslinking reaction by analysising the results of several research methods, but the mechanisms of crosslinking reaction were little difference. Colligating all of the properties and requirments, we believe PEEK containing anthracene moieties have the excellent applied foreground as aromatic crosslinkable poly(aryl ether ketone)s.