Synthesis Of Novel Polybenzimidazoles With Phthalazinone Moieties In The Main Chain

Polybenzimidazole has been noted as a kind of important polymeric material,which presents a combination of outstanding properties,such as high thermal stability,good chemical resistance and excellent mechanical properties.However,the commercial polybenzimidazoles have poor solubility in most organic solvents at room temperature,which resulted in difficulty for processing.In this work,our efforts have been focused on synthesis of polybenzimidazoles with good solubility and high thermal properties by introduction of twisted and non-coplanar phthalazinone moieties into polybenzimidazole backbones.In this thesis,a novel polybenzimidazole containing twist and non-coplanar phthalazinone moieties was synthesized from 3,3'-diaminobenzidine(DAB) and 4-(4-(4-(4-carboxyphenoxy)phenyl)-1-oxophthalazin-2(1H)-yl)benzoic acid(DHPZ-DA). The synthesis process was optimized.After the optimization of the polymerization,the inherent viscosity of this polymer could reach 1.63 dL/g.A series of co-polybenzimidazoles were synthesized by condensation of 3,3'-diaminobenzidine(DAB) with a mixture of DHPZ-DA and isophthalic acid(IPA) in different ratio in polyphosphoric acid(PPA).The polybenzimidazoles were characterized by different instrumental techniques(FT-IR,~1H NMR, WAXD,DSC and TGA).The polymers have good solubility in polar aprotic solvents,such as N-methyl-2-pyrolidinone(NMP),N,N-dimethylacetamide(DMAc),etc.Most of the polybenzimidazoles exhibited amorphous nature as evident by WAXD.The resultant polybenzimidazoles show high thermal stability with the glass transition temperatures of the copolymers from 398℃to 408℃,and the temperatures for 5%weight loss of the copolymers above 516℃.Soluble polybenzimidazoles containing ether linkages and twisted and non-coplanar phthalazinone moieties in the the main chains were successfully synthesized by condensation of DHPZ-DA with 3,3',4,4'-tetramino diphenyl ether(TADE), 1,4-bis(3,4-nitrophenoxy)phenyl(BAPP) and 4,4'-bis(3,4-aminophenoxy)biphenyl(BAPBP) in PPA,respectively.The polybenzimidazoles were characterized by different instrumental techniques.The polymers have good solubility in polar aprotic solvents,such as N-methyl-2-pyrolidinone(NMP),etc.All polybenzimidazoles exhibited amorphous nature as evident by WAXD.The 5%weight loss temperatures for the polybenzimidazoles were all higher than 508℃.