Synthesis and luminescent properties of block copolymers based on polyfluorene and polytriphenylamine

Polyfluorene-poly(ethylene oxide) diblock copolymers: synthesis and electron transport behavior

Under mild reaction conditions, we synthesized diblock copolymers of poly(9,9-dioctylfluorene)-block-poly(ethylene oxide) (PFO-b-PEO) via end-capping poly(9,9-dioctylfluorene) (PFO) with poly(ethylene oxide) (PEO) on one end. We investigated the thermal, optical, electrochemical and crystalline properties as well as electron transport performance of these polymers. Our results demonstrate that PFO-b-PEO diblock copolymers with short PEO chains (M n = 1000 and 2000 g mol-1) exhibit higher electron mobilities compared to the PFO homopolymer and longer PEO chain (M n = 4000 g mol-1) attached copolymers. This enhanced electron mobility is attributed to the higher crystallinity induced by the shorter PEO chain end-capping.

Optical and Thermal Stability of Oligofluorene/Rubber Luminescent Blend

This paper proposes to obtain homogeneous and stable blends of oligo(9,9-dioctylfluorene)-co-phenylene (OF), a conjugated oligomer with strong tendency of formation of excimers in the solid state, and nitrile rubber (NBR). This rubber protection reduces the formation of polymer excimers in the films. The fluorene oligomer was synthesized via Suzuki reaction and incorporated in the nitrile rubber. The films were formed by spin coating and casting techniques on the proportions of 1, 5, 10, 20 and 50 % (w/w) of OF in the nitrile rubber (NBR). The structural, optical and thermal properties of the films were evaluated with infrared, UV-Vis, fluorescence and thermogravimetry, respectively. The nitrile rubber proved to be essential for the preparation of homogeneous and stable films, since it was not possible to obtain films with only fluorene using the above-mentioned techniques. Furthermore, luminescent properties of OF are unchanged and the excimers formation in the solid state decrease suggesting the efficiency of nitrile rubber as the matrix for making films.

Synthesis and characterization of novel cross-linking light-emitting polyfluorene derivatives

Polyfluorene derivative with amine side groups, namely, P1 was synthesized by the palladium-catalyzed coupling reaction of 2,5-dibromoaniline with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9′-dioctylfluorene. Cross-linked polyazomethine P1-TPD (cross-linked polymer, P1/ terephthalic aldehyde) was obtained by the reaction of P1 with terephthalic aldehyde. Given that replacement of the phenylene ring by a thiophene ring can improve π-electron delocalization, we also synthesized P1-TPCD (cross-linked polymer, P1/ 2,5-thiophenedicarboxaldehyde) whose cross-linking bridge was a thiophene ring. The ultraviolet–visible spectra of P1-TPD showed that there was a little hypsochromic shift to its pristine polymer P1, however, the maximum emission wavelength was changed to the second peak in the photoluminescence spectra. Besides, the band gap energy ( Eg) of P1-TPD was a little narrower than that of P1. The maximum absorption wavelength and the maximum emission wavelength of P1-TPCD was almost the same with P1, but its Eg was narrower than P1 and P1-TPD. Most notably, azomethine-linked P1-TPD and P1-TPCD were fluorescent with measured fluorescent quantum yields of 22% and 44%.