Synthetic Studies And Exploration Of New Monomers Used In PBO And Polymer Modified By Imidazol-Hydroxy Structure

Poly-p-phenylenebenzobisthiazole(PBO) as the super fiber in 21 centry, its excellent tensile strength,high temperature resistance and application has become a hotspot research. In this paper, for the current existence of compressive poor performance, lack of bonded composite and technological monopoly in PBO fiber, new monomer for preparing PBO and its modified hydroxy-imidazole polymer was researched and explorated.First, based on AB-PBO new monomer:4-(5-Amino-6-hydroxy-benzoxazol-2-yl)benzoic acid(ABA) successfully obtained, its synthesis technology was optimized and its polymerization process for preparing PBO polymer in self-reactor was explored. The results showed that:the new technology of synthesis ABA was convenient and economic which was used methyl 4-(5-nitro-6-hydroxybenzoxazol-2-yl)benzoate (MNB) as raw material, via K2CO3 hydrolysis and under alkaline conditions to restore, with purity 98.6%, yield 78.7%, refine purity 99.28%, refine yield 92.6%, the whole yield 72.88% based on MNB. With ABA as raw material in the presence of 85% P2O5, by 90℃,120℃,150℃,180-200℃temperature-programmed reaction 13 hours, the PBO resin viscosity was greater than 11dL/g which showed good results.Based on "M5" hydrogen bonds between molecules and composite bonding, as well as polybenzimidazole(PBI) Solubility, we explored series of new monomers of modifiable PBO polymer which had the imidazole and hydroxy groups structure. The results showed that:1) The process that hydroquinone as starting material in the solvent-free system to prepare BB-type monomer 2,5-dihydroxyterephthalic acid (2,5-DHTA) was researched, and refined with purity 99.6%, yield 51%, which achieved polymer-level. Initially developed the synthesis technology of AA-type monomer 1,2,4,5- tetraaminobenzene (TAB), HPLC purity 98%, which can replace expensive 1,2,4,5-tetraaminopyridine (TAP). It provided a new type of monomer for economic preparation of new polymer which had similar structure and properties as "M5".2) In the innovative design of AB-type polyp-phenylenebenzo imida-oxadizole (PBIO) monomer which had both the PBO and PBI performance, its synthesis methods was explored and its key intermediate 3-amino-4,6-dinitrophenol(ADNP) was successfully prepared; Otherwise Na2S2O4 was chose as reducing agent, and brought out a highly selective nitro reduction, prepared AB-type intermediate 4,5-diamino-2-nitrophenol (DANP), purity above 95%, yield 70%; provided sources of intermediates for further study new PBIO monomers.Series of new monomers and intermediates molecular structure were confirmed by IR,1H-NMR and MS analysis.