Synthesis, characterization, luminescence properties and thermal studies of polyaniline and polythiophene composites with rare earth terbium(III) complex

• In situ oxidative polymerization method was used for synthesis of polymer composites.
• Various crystallographic parameters were calculated.
• Chelated terbium complex (used as a dopant) showed narrow emission lines.
• Polymer composites exhibited better emission properties than undoped pure polymers.
• Thermal stability of polymer composites was found better than undoped polymers.

In situ oxidative polymerization technique has been used to synthesize the conducting polymers of polyaniline, polythiophene and their composites. Rare earth metal complex of terbium(III) is synthesized by refluxing method and characterized by elemental analysis, conductance measurement, FTIR and thermogravimetric analysis. Powder XRD shows polycrystalline nature of dopant (terbium(III) complex) and its distribution in polyaniline and polythiophene matrix is well evident from XRD and SEM. Lattice parameters a, b, c and α, β and γ have been calculated using powder X software for the dopant as well as the composites. Various parameters like interplanar distance (d), crystallite size (L) and dislocation density (ρ) have been also calculated by Bragg’s and Scherrer’s equations. The calculated d spacing values are in agreement with the experimental d spacing values. Terbium complex shows narrow emission bandwidths in DMSO solution. The good fluorescence of terbium complex might be due to the antenna effect of ligands. The luminescence properties of polymer composite of polyaniline and polythiophene have been investigated by UV–vis and fluorescence spectra. The experimental results of fluorescence show that polyaniline composite emit purple/green fluorescence in N-methyl 2-pyrolidone and polythiophene composite emit also purple/green fluorescence in DMSO solution at room temperature. The good thermal stability and fluorescence property of dopant and polymer composites are very important aspects for their technologic applications as luminescent probes or light emitting diode materials.

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