Synthesis And Properties Of Poly (Aryl Ether Ketone) Copolymers Containing Phthalazinone Moieties

Recently, a novel kind of poly(aryl ether ketone) material containing phthalazinone moiety was developed by our research team. It is a kind of high-performance engineering thermoplastics with reasonable solubility and excellent thermal property. It possesses a promising future in the applications of industry. Starting from the design in molecular structure, a series of poly(aryl ether ketone) block copolymers containing phthalazinone moiety were prepared by us. These block copolymers possessed both PPEKK's excellent properties and PEEKK's prominent properties. Furthermore, based on the excellent property of phthalazinone structure, two novel kinds of poly(aryl ether ketone) thermotropic liquid crystalline copolymers and lyotropic liquid crystalline copolymers were also synthesized by us.A series of poly(aryl ether ketone) copolymers were prepared by a two-step high temperature solution polycondensation reaction with 1,4-bis(4-fluorobenzoyl)benzene(BFBB), 4-(4-hydroxyl-phenyl)(2H)-phthalazine-1-one(DHPZ) and hydroquinone. The copolymers could be soluble in some common polar aprotic organic solvents when the content of phthalazinone reached 60mol% in the main chains. As the content of phthalazinone in the main chains varied from 10mol% to 90mol%, the glass transition temperatures of the copolymers increased from 168℃to 235℃, and the melting temperatures decreased from 352℃to 285℃. The temperatures for 5% weight loss for the copolymers were all higher than 510℃. The crystal structure of the copolymers was belonged to orthorhombic system, the degree of crystallinity decreased from 28.46% to 10.12% gradually. The values of B which was calculated by the results of ¹³C NMR were all close to 1 indicated that the copolymers were random copolymers in structure. The HAAKE torque value of PAEK64 is much lower than that of pure PPEKK resin at the same measurement conditions; meanwhile, the tensile strength of PAEK64 is 82.82 MPa.The high temperature solution polycondensation reaction was carried out with PPEKK oligomers and PEEKK oligomers as "polymer monomer" which was synthesized in advance. And two kinds of block copolymers were prepared by this reaction successfully. The results incicated that the polymers obtained were the block copolymers of PPEKK oligomers and PEEKK oligomers, the structure was the same as designed structure. The block copolymer(BlockI) could be soluble in N-methyl-pyrollidione(NMP) at 160℃when the molecular weight of PPEKK reached 12,000g/mol in the main chains, they could not be soluble in NMP at room temperature. The block copolymer(BlockII) could be soluble in chloroform at room temperature when the molecular weight of PPEKK reached 18,000g/mol in the main chains. The glass transition temperature of BlockI was 240℃, the melting temperature was 345℃, and the glass transition temperature of BlockII was 242℃, the melting temperature was 342℃. The temperatures for 5% weight loss for the copolymers were all higher than 515℃. The crystal structure of the block copolymers was belonged to orthorhombic system, and the interplaner spacings were all larger than pure PEEKK. The value of B which was calculated by the results of ¹³C NMR for BlockII was 0.69 indicated that the copolymer was block copolymer in structure, and the structure was in agreement with designed structure. Compared with pure PPEKK the melt viscosity of BlockII decreased 96% and lower than that of PAEK64, at the same time the tensile strength of BlockII was 89.35MPa.A series of phthalazinone-containing thermotropic liquid crystalline poly(aryl ether ketone) copolymers were developed by a high temperature nucleophilic substitution with biphenyl as potential mesogenic unit. When the content of phthalazinone in the main chains was between 20～80mol%, the copolymers exhibited characterisitic thermotropic nematic liquid crystalline texture. There were two reversible first-order thermo transitions in the DSC curves of the themotropic liquid crystalline copolymers. The first transition was belonged to the crystal phase to liquid crystal phase and the second transition was belonged to the liquid crystal phase to the isotropic phase transition in the heating programme. The temperatures for 1% weight loss for the copolymers were all higher than 490℃. The crystal structure of the copolymers was belonged to orthorhombic system. The liquid crystalline phase of the copolymers was belonged to nematic liquid crystalline. The thermotropic liquid crystalline PAEK copolymers exhibited characteristic nematic droplet texture when annealed at their liquid crystalline phase for 1h, and the droplet texture changed into banded texture or schlieren texture when shear forces were induced.A series of lyotropic liquid crystalline poly(aryl ether ketone) copolymers were successfully synthesized by a two-step high temperature solution polycondensation reaction with DHPZ as crystal disrupting unit and biphenyl-4,4'-diol as mesogenic unit. The NMP solutions of the copolymers exhibited typical lyotropic liquid crystalline phase when the content of phthalazinone in the main chains varied from 60mol% to 85mol%. The critical concentration (C^*) of these copolymers increased with the increasing of phthalazinone content in the main chains, the clear point temperature increased with the increment of the copolymer concentration in NMP. The results of WAXD indicated that the liquid crystalline phase was nematic phase in nature. The copolymers exhibited typical thermotropic liquid crystalline phase when the content of phthalazinone in the main chains varied from 30mol% to 60mol%. The results of WAXD indicated that the liquid crystalline phase was nematic phase in nature. The temperatures for 1% weight loss for the copolymers were all higher than 490℃.