Synthesis and thermo-stability investigation of blue electroluminescent poly(9,9′-dioctylfluorene) end-capped with hindered amine light stabilizer

A novel hindered amine light stabilizer has been synthesized using 1,2,2,6,6-pentamethyl-4-piperidinol and 4-bromobenzoyl chloride as the raw materials, and has been utilized to end-cap the blue electroluminescent poly(9, 9′-dioctylfluorene). The chemical structure of the polymer has been characterized with nuclear magnetic resonance(¹H-NMR) and gel permeation chromatograph (GPC). Its thermo-stability was investigated by comparing the fluorescent spectra after annealing at elevated temperature in air. It clearly demonstrated that the light fluorescent spectroscopic stability of the polymer was greatly improved and the common phenomenon of greenish blue emission has been effectively restrained after end-capped with the hindered amine light stabilizer.