Fluorene-bridged polyphenylquinoxalines with high solubility and good thermal stability: Synthesis and properties

 A novel fluorene-bridged tetraketone monomer, 9,9-bis(4-benzilyloxy)phenyl]fluorene (FLTK) was synthesized and characterized. The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyphenylquinoxalines (PPQs). The obtained polymers were found to be soluble in common organic solvents such as N-methyl-2-pyrrolidone (NMP), chloroform and m-cresol. Flexible and tough PPQ films obtained by spin-casting their NMP solutions exhibited tensile strengths higher than 60 MPa. The films also demonstrated good thermal stability up to 500^oC in nitrogen and glass transition temperatures higher than 280^oC. In addition, the PPQ films exhibited good hydrolytic stability. High surface and volume resistivity retentions were achieved for the films after immersion or boiling in water for 24 h.