Study On Novel Polybenzimidazoles Containing Phenyl Phthalazinone Moieties

Polybenzoimidazole is considered as a high performance engineering plastic of good combination property, because of its excellent thermal stability and mechanical properties. It has been applied in many fields’such as aerospace, electronics, the fuel cell proton exchange film and so on, and thus been an important material for economy, sophisticated technique and high technical industry. However, the commercial PBI is insoluble and infusible, resulting the difficulty in processing, and its application in other fields is confined. In this thesis, the kink and non-coplanar phenyl phthalazinone moieties have been introduced into PBI main chains. And a series of novel PBIs with good solubility and high thermal properties were synthesized successfully.Firstly, oP-DHPZ-DA is synthesized from biphenol monomer oP-DHPZ via nucleophilic substitution and alkaline hydrolysis reaction. Then, PBI containing phenyl phthalazinone moieties is synthesized by the solution polycondensation reaction of diacid monomer (oP-DHPZ-DA) and3.3"-diaminobenxidine (DAB). The diacid monomer is confirmed by FT-IR、1H-NMR、13C-NMR,1H-1H COSY and MS technologies, and all of the spectral data have proved its structure. WAXD shows that the polymer possess amorphous structure. It is soluble in concentrated sulfuric acid, methanesulfonic acid, NMP and so on. The glass transition temperature of the polymer is390oC and the5%thermal weight loss temperature is529oC in nitrogen. Thus, the PBI with phthalazinone mostly possesses excellent thermostability and good solubility.A series of PBI with phenyl phthalazinone structure are synthesized from the reaction of4,4’-oxybis(benzoic acid), oP-DHPZ-DA and DAB in PPA in different molar ration of diacids. The characterization of structure and performance shows that the PBI is of amorphous structure and possesses excellent thermostability and mechanical property. The glass transition temperatures are between352oC and390oC. And the5%thermal weight loss temperatures are between528oC and579oC. The values of glass transition temperature increase with the increase of DCDPE content. In addition, the solubility is improved.A series of PBI copolymers with hexanfluorineisopropyl and phenyl phthalazinone structure are synthesized from the reaction of4,4’-(hexafluoroisopropyl-idene) bis(benzoic acid), oP-DHPZ-DA and DAB in PPA in different molar ratio of diacids. The structural characterization and performance measurement show that the PBI is of amorphous structure and possesses excellent thermostability via FT-IR, DSC, TGA and WAXD. The glass transition temperatures are between403°C and406°C. And the5%weight loss temperature ranges from530°C to542°C in nitrogen.