Molecular Design, Synthesis And Properties Of Poly (Benzobisoxazole)s Containing Phthalazinone Moieties

In this paper, a new type of monomer 2-(3-hydroxyl-4-amino-phenyl)-4-[4-(3-hydroxy-4-amino-phenoxy)-phenyl]-phthalazin-l-one (DAH) containing phthalazinone moieties was designed and synthesized by three-steps using 2- nitro - 5- fluoro phenol and 4-(4-hydroxyphenyl)-1(2H)-phthalazinnone (DHPZ) as raw materials. The synthesis processes of intermediates and the monomer DAH were characterized by different instrumental techniques (FT-IR,1H NMR and MS). The results showed that the structure of monomer was the same as designed.Polymer PBOTA and PBOFA containing phthalazinone moieties were synthesized in polyphosphoric acid (PPA) by condensation polymerization between DAH and terephthalic acid (TPA), fumaric acid (FA). The synthesis processes of PBOTA and PBOFA were optimized. The structure of PBOTA and PBOFA were characterized by different instrumental techniques (FT-IR,1H NMR). The results showed that the structure of PBOTA and PBOFA were the same as designed.The synthesized polymer PBOTA and PBOFA had high molecular weight, and their maximal intrinsic viscosity were 14dL/g and 7dL/g. PBOTA could dissolve in metacresol on heating, and PBOFA could dissolve in metacresol at room temperature, which showed that the solubility of the polymers had greatly improved. The polymer performances were characterized by thermal gravimetric analyzer (TGA), UV spectrum (UV) and wide angle X-ray diffraction (WAXD). The results showed that the 5% weight loss temperatures of PBOTA and PBOFA were 518℃and 468℃.The 10% weight loss temperatures of PBOTA and PBOFA were 560℃and 510℃. The maximum thermal weightlessness temperatures were above 500℃. These datas indicated PBOTA and PBOFA had good thermostability. The UV spectrums of polymer PBOTA and PBOFA were red shift compared with the monomer DAH. Both PBOTA and PBOFA exhibited lyotropic liquid crystalline behavior in concentrated H2SO4. XRD dates showed that PBOTA and PBOFA had not crystallinity.