Synthesis and Characterization of Polybenzobisoxazole Polymers Containing Trifluoromethyl or Sulfone Groups

Two series of polybenzoxazoles (PBOs) containing trifluoromethyl or sulfone groups were synthesized via solution condensation polymerization. The polymers were characterized by FT-IR, ¹H-NMR, thermogravimetric analysis (TGA), UV-vis absorption, and photoluminescence (PL) spectroscopy. The solubility of these polymers was greatly enhanced over that of pure PBO and some of them could dissolve well in polar solvents, such as N-methyl-2-pyrrolidone (NMP) and 2,5-Dimethylfuran (DMF). Due to the introduction of trifluoromethyl and sulfone groups, the UV absorption peaks and the emission peaks of all the polymers blue shifted, compared with those of pure PBO. The polymers derived from 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP) had a lower dielectric constant, which is due to the strong electron-withdrawal inductive effect, compared to that of the polymers derived from 3,3-diamino-4,4-dihydroxydiphenylsulfone (6SAP).