Synthesis of New Star-Shaped Polymers with Styrene-Fluorene Conjugated Moieties and Their Multicolor Luminescent Ordered Microporous Films

We report the synthesis, photophysical properties, and morphology of new star-shaped polymers with styrene-fluorene (St-Fl) conjugated moieties. Three polymers with different number of arms (P(St-Fl)(n), n = 3, 4, and 8) were obtained by living anionic polymerization, and they exhibited a narrow molecular weight distribution (M-n/M-w < 1.06). The effects of arm numbers, humidity, and solution concentration on the formation of the microporous structures were studied. It was found that the high molecular weight P(St-Fl)(8) could form a highly ordered microporous film via drop-casting, but not on the polymers with the other two arm numbers. In addition, the pore diameter was reduced while enhancing solution concentration or decreasing humidity. Relatively uniform blue-emitting characteristics were obtained on the P(St-Fl)(8) microporous films. Such highly ordered structure led to a red shift in photophysical properties, such as absorption and photoluminescence. Furthermore, green-and red-emission microporous films were obtained via blending a relatively small amount (similar to 1 %) of poly((9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-(2,1',3)-thiadiazole) or bis(1-phenylisoquinoline)(acetylacetonate)irdium(III) (Ir(piq)(2)(acac)) through efficient energy transfer. The experimental results suggested a new approach to synthesis of star-branched polymers with pendant conjugated moieties and the formation of the multicolor ordered microporous films.