Effect of the Chain Length on the Photonic Efficiency of Aromatic-Aliphatic Dendronized Polyethers (original) (raw)
Related papers
Polymer Bulletin, 2018
Rapid synthesis of new fluorene-based conjugated polymers P1-P8 is reported by polymerization of polyphenylene-substituted dendronized monomer 2,7-dibromo-9,9-di(4-(2,3,4,5-tetraphenylphenyl)-benzyl) fluorene (M1) and 2,7-dibromo-9,9-di(4-pentaphenylphenyl)-benzyl) fluorene (M2) with different 9,9-disubstituted 2,7-dibromo fluorene monomers (M3-M6) under microwave irradiation. The structure of these synthesized polymers P1-P8 was established by FTIR, 1 H NMR, 13 C NMR, and gel permeation chromatography techniques. The photophysical studies of these polymers P1-P8 shows good results desirable for light-emitting material. These polymers exhibited UV-Vis absorption peak with the maxima in 344-386 nm in THF solution. Similarly, the fluorescence spectra of these polymers showed PL maxima in 414-418 nm with shoulder peak in 437-440 nm. From this study, the stoke shifts was observed in 30-73 nm, and quantum efficiency was found in 0.41-0.57. Polymers had thermal stability up to 200 °C; however, for dihexyl-substituted dendronized polymer, P1 and P5 showed thermal decomposition at 490 and 430 °C, respectively. In addition to this, polymers P1-P8 were also analyzed by electrochemical study in which the onset of the irreversible oxidation wave of dendronized polymers P1-P8 is recorded in the range of 0.88-0.99 V. The results of these various studies showed that the synthesized polymers P1-P8 can be promising materials for blue-light-emitting diodes because of their high photoluminescence (PL), quantum efficiencies, and thermal stability.
Journal of Luminescence, 2001
This work describes the photophysical properties of a new series of blue-emitting rigid-flexible polyethers in solution and in thin films, namely, poly(2 00 ,5 00 -dihexyloxy-p-quinquephenyl-4,4 0000 -a,o-dioxyalkylene). These polymers have high fluorescence yields and spectroscopic properties that can be tailored by choosing the appropriate rigid-flexible segment size. The polymers demonstrate a marked odd-even effect for both glass transition temperature and fluorescence quantum yield with respect to spacer length. Odd-even effects are usually observed in the solid state but the present polymers demonstrate odd-even effects in fluorescence efficiency even in solution. In addition, extensive spectral narrowing by waveguide gain can be obtained with a member of the series when deposited in a thin film. Their properties make these polymers interesting candidates for photonic applications. #
Journal of Polymer Science Part A: Polymer Chemistry, 2007
An inexpensive and highly efficient synthesis of first example of fluorescent aromatic dendrimers having alternative ether and urea linkages without the need for protection and deprotection steps has been developed. Dendrons and dendrimers up to third generation, with amine end-groups, were prepared by convergent growth approach in high yield. A repetitive synthetic sequence of nucleophilic addition reaction between amine and regenerated isocyanate and reduction of nitro groups into amine are adopted for the synthesis of these dendrimers. The peripheries of the dendrimers contained 6, 12, and 24 amino groups, for the first, second, and third generation, respectively. Materials were characterized by FTIR, NMR, and MALDI-TOF MS spectrometry. These dendrimers were soluble in amide solvents, THF and acetone and displayed fluorescence maxima in the 440-500 nm range with relatively narrow peak widths indicating that they had pure and intense fluorescence. These dendrimers form chargetransfer (CT) complexes with electron acceptor molecules such as 7,7,8,8,-tetracyanoquino-dimethane and 1,1,2,2 tetracyanoethane as evidenced by UV-visible absorption spectra. V
Functional Aromatic Polyethers: Polymers with Tunable Chromogenic and Fluorogenic Properties
Macromolecules, 2010
This paper describes the preparation and chemical modification of pyranone-based aromatic polyethers to yield polymers that contain pyrylium rings, which permit the design of high performance materials with "a la carte" chromogenic and fluorescence behavior. These materials can be used for innovative applications such as luminescent converter (LUCO) materials for hybrid light-emitting diodes (LEDs) or the preparation of selective chromogenic and fluorogenic sensing materials for the preparation of sensing devices. The fluorescence emission maxima of polyether films ranged from 514 to 561 nm, allowing the future development of LUCO-LED devices. Moreover, the interaction of polyether films with different amines leads to color changes and variations in the intensity and emission maxima of fluorescence, which permits the development of amine sensing materials.
European Polymer Journal, 2007
A series of alternating fluorene and p-phenylenevinylene copolymers containing non-conjugated spacer have been synthesized through the Wittig polycondensation reaction. These amorphous copolymers are highly soluble in common organic solvents and can be spin-cast to obtain transparent films. The effects of non-conjugated spacers in the main chain and the methoxyl groups on the side chain on the thermal behavior, photoluminescence (PL) and electroluminescence (EL) properties of these copolymers have been investigated in detail. Single-layered light-emitting diodes (LEDs) have been fabricated in the configuration of ITO/PEDOT/copolymer/Ca/Al and emitted blue light in the range of 456-492 nm. The measurements of current vs voltage show turn-on voltages at 6.2-12.4 V. Among the LEDs based on the six copolymers, the maximum EL brightness and efficiency of the LED based on P1 containing 4CH 2 aliphatic segment length in the main chain and without methoxyl groups on side chain are reached 3936 cd/m 2 and 0.70 cd/A, respectively.
Novel side chain dendritic aromatic-aliphatic polyethers are synthesized from aromatic terphenyl diols, disubstituted with Fréchet-type dendrons of the first and second generation and aliphatic dibromides of various lengths. High-molecular-weight soluble polymers were obtained in all cases. The bulk properties of the polymers were examined by means of thermal analyses (DSC), dynamic mechanical analyses (DMA), and X-ray diffractometry. Separation between the main chain and the dendritic side chains was evident due to the existence of two well-resolved glass transition temperatures, observed by both DSC and DMA measurements.