Project Title: "Conductive elastomeric blend of natural rubber and polyaniline derivative"

Author: Matthieu Depret, Université de Valenciennes et du Hainaut-Cambrésis, France

Host Supervisor: Dr. José Antonio Malmonge, Universidade Estadual Paulista “Júlio de Mesquita Filho” UNESP, Brazil

Nowadays processing conducting polymers in form of blends and composites with commercial polymers is a well-established alternative as material for technological applications. By combining the high electrical conductivity of one with thermal stability, good mechanical properties and processability of conventional polymer, several blends have been produced with interesting properties. Polyaniline (PANI) and its derivate are one of the most interesting conducting polymers that have attracted considerable attention because of its good environmental stability, the control of the electronic and optical properties via the level of oxidation and protonation, low cost of raw material, and ease of synthesis. In this work conductive elastomeric films have been prepared by mixing a solution of natural rubber (NR) dissolved in chloroform (CHCl3) with a solution of
poly(o-methoxyaniline) (POMA), a polyaniline derivative, dissolved also in CHCl3, at  different  proportions. The final solution was casting onto Teflon mould placed in an oven with air circulation, at room temperature. After solvent evaporation the film obtained was removed from the Teflon mould by peeling them out.  The primary doping of POMA was done by mixing it with dodecylbenzene sulfonic acid (DBSA). Physical characterizations of the films were realized by Fourier transformed infrared (FTIR) and UV-Vis-NIR spectroscopy, Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), X-ray diffraction and two prove electrical conductivity. The higher value of the electrical conductivity obtained was 10-5 S/cm, nine orders in magnitude higher compared with pure NR. The UV-Vis-NIR and FTIR spectra of the blend are similar to the doped POMA, indicating that the POMA is responsible for the high electrical conductivity of the blend. The DSC thermograms showed the glass transition of the blends around –610C, characteristic of the natural rubber, independent of blend composition. X-ray diffactograms and SEM micrograph showed that the presence of the NR in the blend do not affect the formation of the POMA phase.