Fluorene-Based Poly(imino ketone) with Fluorine Atoms on the Side Chains as an Intelligent High-Performance Polymer

Fluorene-based poly(imino ketone) with fluorine atoms in the side chains (PIKF-F), as an intelligent, high-performance polymer, was synthesized by the reaction of 4,4′-dibromobenzophenone and 9,9-bis(3-F-4-aminophenyl) fluorene via a palladium catalyzed C-N cross-coupling reaction. Its structure was characterized by means of FT-IR and 1H NMR spectroscopy. The results showed a good agreement with the proposed structure. The molecular weights of the PIKF-F were measured by GPC (calibrated by polystyrene standards). The Mn and Mw values were 64,800 and 153,300, respectively. Thermogravimetric analysis and differential scanning calorimetry measurements showed that the polymer possessed good thermal stability with a high 10% decomposition temperature (450 °C) and a high glass transition temperature (Tg = 250 °C). The PIKF-F exhibited UV (ultra violet) absorption bands at 340–370 nm in NMP solution, while the fluorescence spectra showed maximum emission of PIKF-F at 498 nm in NMP solution. Both optical properties indicate the PIKF-F is of potential use as an organic photoelectric material. Additionally, due to its special conjugated system and the intramolecular hydrogen bonding (N–H···F), it was endowed with significantly strong photonic luminescence and the change of fluorescent intensity was reversible as the temperature was changed.