Synthesis of novel copolymer (nano)composite based on N-vinylcarbazole and black eriochrome using electro-polymerization method

This study reports the successful synthesis of a new copolymer based on N-vinylcarbazole (NVC) and Eriochrome black T (EBT) monomers as well as (nano)composites based on carbon nanotubes (CNTs) as nano-filler. For this, the copolymer poly (N-vinylcarbazole-co-black eriochrome T), noted poly (NVC-co- EBT) was synthetized by electro-copolymerization of the selected monomers deposited on Indium Tin Oxide (ITO) electrode in lithium perchlorate electrolyte, using cyclic voltammetry method. The (nano)composites poly (NVC-co- EBT)/CNTs were synthesized in the same conditions as the copolymer, in presence of different CNTs content (3 wt. %, 5wt. %, 10 wt. %). The electrodeposition of the copolymer (nano)composites was successfully occurred after the first cycle and thin films were formed. Remarkably, their thickness was increased by increasing the cycle’s numbers. The electro-chemical properties of the new copolymer, as well as (nano)composites, were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The synthesized (nano)composites display a diffusion process related to Warburg impedance, for a low and intermediate frequencies but they exhibit a capacitive behavior at high frequencies which implies the increase of the conductivity character. Furthermore, the obtained copolymer poly (NVC- co - EBT) exhibits low transmittance in the UV–visible region, with a gap energy value of 1.95 eV. Interestingly, by doping with CNTs nano-filler at 3 wt. % and 5 wt. %, the energy gap was relatively increased to achieve a value of 2.41 eV and 2.71 eV, respectively. Therefore, at 10 wt. % of CNTs, the energy gap of the copolymer (nano)composite becomes equal to zero. Consequently, these results highlight the importance of the synthesized copolymer to have a semi-conductor and conductor behavior according to the CNTs content in the material, which promote its application in many devices, as photocatalysis and photovoltaic fields. Graphical abstract