Toward Thermally, Oxidatively, and Spectrally Stable Polyfluorene-Based Materials: Aromatic Ether-Functionalized Polyfluorene

Two unique fluorene monomers (PTE and MTE) and polyfluorene-based homopolymers (PPTE and PMTE) containing covalently linked aromatic ether (AE) moieties were synthesized via microwave Ni(0)-mediated Yamamoto coupling reactions. The monomers and polymers demonstrated thermal stabilities, as determined by TGA, much higher than status quo poly(9,9′-dioctylfluorene) (PFO) (i.e., greater than 100 °C), and most importantly, the spectral emission remained stable after annealing in ambient and inert atmospheres. PPTE and PMTE were annealed in an N₂ atmosphere at 200 °C for 72 h and at 150 °C in ambient atmosphere for 1 h showing no evidence of green emission, in stark contrast to PFO. The results show that PFs with AE moieties present in the 9-position exhibit stable blue emission.