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ABSTRACT
A new series of polyaniline based nanocomposites has been synthesized by using chemical oxidative polymerization of aniline (An) with m-trifluoromethyl aniline (TFMA) doped dodecylbenzene sulphonic acid (DBSA). The prepared copolymer composites were characterized by using different analytical techniques such as UV-visible, FT-IR, Scanning electron microscopy (SEM), X-ray diffraction methods (XRD) and humidity sensing techniques. The Conducting properties of these nanocomposites was studied by using standard four probe method. The particle size ranges from 100 nm to 200 nm diameters was observed in SEM analysis and surface morphology shows solid granular layers of nano pillared like structures. XRD pattern shows that the amorphous nature of the copolymer particles. Interestingly the electrical conductivity of this nanocomposite was found to be 1.807 × 10-4 S/cm. The solubility tests of these composites show good solubility than that of polyaniline homopolymer. The humidity sensing mechanism was studied, based upon the resistance variations due to the absorption of water vapour. The poly (An-co-m-TFMA) thin film was prepared by spin-coating method and humidity sensing ability was compared. It was observed that by the change of relative humidity (%RH) from 10% to 70%.
Keywords: Aniline, m-Trifluoromethyl aniline, Nanocomposites, SEM, Humidity sensor
1.INTRODUCTION
In recent years there has been a research interest in the field of nanostructured polymer composites. Also there is an immediate need to develop an advanced material for the industrial applications for sustainable development. The various nanoscaled morphologies such as nanosphere, nanotubes, nanofibres, nanowires and nanorods possess fascinating physiochemical properties.[1,2] These polymers possess unique electrical and magnetic properties leading to wide range of industrial applications such as sensors, rechargeable batteries, electromagnetic shielding, light emitting diodes and solar cells.[3] Among the different conducting polymers, polyaniline is the most popularly studied polymers because of its easiest synthesis method, high conductivity, good environmental stability and thermal stability.[4, 5] Polyaniline exists in three forms namely, emeraldine salt, leucoemeraldine and pernigraniline. Among them emeraldine salt is of conducting nature, whereas leucoemarldine and pernigraniline are to be non-conducting. However, the main problem in PANI is that inadequate industrial processability due to poor solubility in various organic solvents.[6-8] The stiffness of the polymer chain makes difficulties in the processability. To overcome this problem many research works have been done such as copolymerization and preparing aniline...