New Polyquinoline Copolymers: Synthesis, Optical, Luminescent, and Hole-Blocking/Electron-Transporting Properties

Abstract

A series of polyquinolines containing the 9,9-di-n-hexylfluorene unit in the main chain were synthesized via Friedländer quinoline synthesis in good yields. The thermal, optical, luminescent, electrochemical, and hole-blocking/electron-transporting properties of these polyquinolines were examined. The glass transition temperatures (Tg) were in the range 195−243 °C, and these polyquinolines had initial decomposition temperatures of >388 °C. Their optical and luminescent properties varied with the chain rigidity and conjugation length. Cyclic voltammetry studies reveal that these polyquinolines undergo irreversible oxidation onset around −6.0 eV, and their LUMO level ranged from −2.78 to −3.21 eV. The application of two of these polyquinolines as a hole-blocking/electron-transporting layer in polymeric LEDs was demonstrated.