Syntheses And Characterization Of Novel Polybenzimidazoles

In this thesis, recent progress related to the synthesis, modification and application prospect of polybenzimidazoles (PBI) is briefly outlined. In this research, the compounds 3,3',4,4'-tetramino diphenyl ether (TADE) or 3,3',4,4'-tetramino diphenyl ether hydrochloride, 4,4'-dicarboxylate diphenyl ether(DCDE),2,5-pyridine dicarboxylicacid or 2,6-pyridine dicarboxylicacid have been used as monomers and trimesic acid as crosslinking agent to prepared a series of PBI polymers.The detailed contents and the results are given as follows.1. Starting from raw material 4,4'-diamino diphenyl ether, the monomer 3,3',4,4'-tetramino diphenyl ether was synthesized via acetylization, the nitration, reduction, and hydrolysis. To obtain higher yield, the corresponding preparation conditions have been opitimized. All immediate compounds were characterized by FT-IR,1H NMR spectra.2. Starting from raw materials p-chlorotoluene and p-methyl phenol, the monomer 4,4'-oxydibenzoic acid was synthesized via Ullmann coupling reaction. The parameters related to preparation process such as the feed ratio, alkaline type and reaction time have been optimized.3. Novel PBIs have been prepared by polymerization reaction between the monomer 3,3',4,4'-tetramino diphenyl ether and 4,4'-oxydibenzoic acid,2,5-pyridine dicarboxylicacid or 2,6-pyridine dicarboxylicacid in polyphosphoric acid under nitrogen atmosphere. To improve the properties of PBIs, the trimesic acid was used as crosslinking agent in different weight contents. All synthetic PBIs have been characterized by FT-IR spectrum, TGA and and viscosity test. The solubility of prepared PBIs in different solvent has been tested as well.