Synthesis, solid-phase reaction, optical properties, and patterning of luminescent polyfluorenes

The homopolymer of 9,9-di(2-(2-tetrahydropyranyloxy)ethyl)fluorene and copolymers based on 9,9-dihexylfluorene, thiophene, and 3-(2-(2-tetrahydropyranyloxy)ethyl)thiophene repeat units were obtained as patternable blue, green, and blue-green color luminescent polymers. Thermolytic and acid-catalyzed removal of the bulky tetrahydropyran (THP) group from thin solid films of the polymers was investigated. The acid-catalyzed deprotection can be carried out at a significantly lower temperature than thermolytic deprotection in the absence of acid. The effect of the acid-catalyzed deprotection of these polyfluorenes (PFs) on the photoluminescent properties was studied. Prior to deprotection, the polyfluorenes show good optical properties and high emission intensity both in solution and in the solid state. After deprotection, their optical properties were retained and their quantum yields of photoluminescence remained high, but their solubility was reduced due to the presence of hydroxyl groups. The decrease in solubility allows for their spatially controlled deposition using chemically amplified soft lithography.