Influence of Dibenzoyl Tartaric Acid on the Electrical Performances of the Polyaniline

Abstract

In this study, the dibenzoyl-L-tartaric acid (DBTA) was used as doping agent to synthesis polyaniline (PANI) by direct oxidative polymerization of a chiral aniline monomer repeat unit. The influence of DBTA on the electrical performances of the polyaniline was studied with the synthesis conditions, particularly the molar ratio of DBTA to aniline and the presence of methanol. The spectral characterization (FT-IR and UV-visible-NIR), the thermal (TGA), electrical properties at macroscopic scale (I-V, C-V curves and the gap) and the morphology of the PANI have been investigated. From the results it's found that synthetic conditions have a great influence on the electrical properties of PANI-DBTA. In addition polyaniline micro-fibres can be obtained when using methanol as a solvent of DBTA. [11][12][13][14][15] and circular polarized electroluminescence (CPEL). [16][17][18] This kind of polymer had the easier ability to give oxidizing and reducing states with colour changes, and the possibility to exchange the physicochemical characteristics with the temperature, pH, and the electric potential. Currently, chiral polyaniline is studied in the literature by different methods like the enantio-selective electropolymerisation of aniline in the presence of (1S) by direct oxidative polymerization of a chiral unit of aniline monomer 22 and by an enzymatic method for production of optically active polyaniline. 23 In the literature it's confirmed that the electronic properties of PANI depends on the degree of protonation and the method of synthesis. 24 Moreover, the work carried out on polyaniline doped by DBTA is based only on the optical properties, 25,26 where the majority of works gave the electric properties of the chiral polyaniline by using an acid containing a sulphonic function and according to Zhang et al.,27 it was reported that the variation of the concentration of the doping agent influences the electric and optical properties of the polyaniline.The aim of this work is to study the electrical behaviour of the polyaniline doped by a chiral acid containing a carboxylic function. The polyaniline was synthesised by direct oxidative polymerization of aniline monomer repeat unit using dibenzoyl tartaric acid (DBTA) as a dopant. The morphology, thermal, spectroscopic and electrical properties of PANI-DBTA were investigated.The DBTA has been chosen here because it has two asymmetrical carbons which confer an optical activity of the polarization plan for the monochromatic light. The optical rotation of DBTA measured in our laboratory at 20 C is À107to À113 in methanol. EXPERIMENTAL ProductsThe products used in this work such as Methanol 99.8%, Aniline 99%, DBTA 99%, ethanol 96%, chloroform 99% are from FLUKA and ammonium peroxydisulfate 99% is from PROLABO. They were all used without purification. Synthesis of PANI-DBTAThe PANI was synthesized by chemical oxidation of aniline, with the ammonium persulfate {(NH 4 ) 2 S 2 O 8 } as oxidant and the (2, 3) di-benzoyl-L-tartarique acid (DBTA) as dopant.In a glass reactor with ...

Polyaniline-doped benzene sulfonic acid/epoxy resin composites: structural, morphological, thermal and dielectric behaviors

“…18 An optical gap in the PANI-doped BSA was determined through spectroscopic analysis by applying the Pankove relation, a(hn)¼A(hn-Eg) 1/2 . 19 By extrapolating the curves to the energy (hn) axis, the value was found to be 1.18 eV, which corresponds to a semiconductor energy gap.…”