References References Multifunctional Polymer Nanocomposites Case Study of Conductive Polypyrrole/SiC Particulate Nanocomposites The combined properties of the polymer nanocomposites can be tailored by the filler materials, filler loadings, surface functionalities of the fillers, and the nature of the polymer matrix. The resulting materials could have unique physical properties, such as improved mechanical strength, increased tensile strength, larger toughness, electrical/thermal conductivity, enhanced clarity, and improved barrier properties and posses wide potential applications. Conducting polymers, such as polyaniline, polypyrrole and polythiophene, have inspired great deal of interests due to their high and tunable electrical conductivity, unique physicochemical properties, easy preparation, high yield and environmental stability. Polypyrrole and its composite materials have been widely used as gas sensors, biosensors, electromagnetic irradiation shielding materials, actuators and artificial muscles, electrode materials, photovoltaic cells, coating materials, and corrosion inhibitors. In this study, a conductive polymer nanocomposite containing polypyrrole and SiC nanostructures was fabricated via oxidative polymerization. The effects of the particle loading and morphology (sphere and rod) of the nanostructures on the physicochemical properties were investigated. Various characterization tools were carried out to explore the material properties Pallavi Mavinakuli 1, Suying Wei 2, Amar B. Karki 3, David P. Young 3, Jewel A. Gomes 1 and Zhanhu Guo 1 * 1 Integrated Composites Lab, Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX 77710, USA 2 Department of Chemistry and Physics, Lamar University, Beaumont, TX 77710, USA 3 Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Polypyrrole Nanocomposites with SiC Nanorods  Materials EXPERIMENTAL INTRODUCTION Polymer nanocomposites are formed by dispersing different functional nanoparticles with exceptionally higher specific surface area as compared to the micron particles into a polymer matrix and have attracted many researchers to explore their potential applications as high-performance materials. Compared to the metal-based nanocomposites and Conventional polymer composites (with filler size larger than 100 nm), polymer nanocomposites have the advantages of easy preparation, light weight, flexible and frequently ductile. The produced polymer nanocomposites have unique physicochemical properties, which are essentially different from those of the components taken separately or a physically combined properties of each component Pyrrole Concluding Remarks In situ oxidative-polymerization approach to fabricate the polymer nanocomposites A strong interaction between SiC nanoparticles and PPy Higher thermal stability in PPy/SiC nanocomposites than that of the pure PPy Tunable conductivity by varying the nanoparticle loading The optimum particle loading for the highest conductivity (0.41 S/cm at RT): 10 wt% The oxidant /monomer mole ratio is the important factor to control the electrical conductivity Ammonium per sulfate P-Toluene sulfonic acid SiC NPs Step 1. NP Oxidant Doping agent Water + Ultrasonic Bath: 60 mins Step 2. + Pyrrole Monomer NP Physical & chemical adsorption of acid & oxidant Fe 2 O 3 NP Oxidation Ultrasonic Bath: 60 mins Characterization X-ray Diffraction Fourier Transform Infrared Spectroscopy (FT-IR) Thermogravimetric Analysis (TGA) Differential Scanning Calorimetry (DSC) Four Point Probe Station Scanning Electron Microscopy (SEM) SELECTION OF FILLER AND POLYMER MATRIX Why Polypyrrole ? High Electrical Conductivity Environmental Stability Ease Synthesis High Yield Tunable Conductivity (dopant and nanoparticles) High Electrical Conductivity Environmental Stability Ease Synthesis High Yield Tunable Conductivity (dopant and nanoparticles) Why Silicon Carbide NPs ? Wide and Tunable Band-Gap semiconductor High Mechanical Strength Good Temperature Thermal Stability Excellent Chemical Resistance High Specific Surface Area Large Hardness Wide and Tunable Band-Gap semiconductor High Mechanical Strength Good Temperature Thermal Stability Excellent Chemical Resistance High Specific Surface Area Large Hardness Polypyrrole Nanocomposites with SiC nanoparticles Phase Structure: XRDFT-IR Spectrometry Thermo Gravimetric Analysis (TGA) Differential Scanning Calorimetry (DSC) Electron Transport Mechanism A linear relationship between the logarithmic resistance and temperature T -1/4 was observed indicating a quasi 3-d variable range hopping (VRH) T 0 is the characteristic Mott temperature σ 0 is the high temperature limit of conductivity The value of n = 4 for 3-dimensional system Electrical Conductivity Shift of band at 1529 cm -1 C=C stretching vibration of PPy to lower band in nanocomposites indicating strong Interaction between SiC nanoparticles and PPy Formation of nanocomposites Poor crystallinity is observed for the nanocomposites with higher nanoparticle loading Resistivity decreases with an increase of the temperature Conductivity depends on the nanoparticle loading Optimum particle loading for the highest conductivity at different temperature was observed to be 10 wt%. Scanning Electron Microscopy (SEM) Effect of Oxidant-to-Monomer Molar Ratio The conductivity decreases with the less oxidant/monomer ratio If the oxidizing strength is too high, the rate of polymerization is too fast resulting in aggregated, low- electrical conductivity material Pure Polypyrrole1.8 wt % NPs 5.0 wt % NPs10.0 wt % NPs The optimum particle loading for the highest conductivity (0.078 S/cm ) at room temperature was observed to be 10 wt% but it is low compare to conductivity (0.44 S/cm) of nanocomposites with NPs loading Difference in morphology between PPy/SiC nanocomposites and pure PPy Thermal stability increased with increase in nanoparticle loading TGA SEM Electrical Conductivity and Electron Transport mechanism No change in glass transition temperature is observed T m decreases with increase in particle loading Pure SiC Nanorod40.0 wt % NRs LAMAR UNIVERSITY A Member of The Texas State University System 1.Z. Guo, K. Shin, A. B. Karki, D. P. Young, and H. T. Hahn, Journal of Nanoparticle Research 11, (2009) M. Omastova, K. Boukerma, M. M. Chehimi, and M. Trchova, Mater. Res. Bull. 40, (2005) R. Gangopadhyay, A. De, and S. Das, Journal of Applied Physics 87, (2000) S. Dhage, H.-C. Lee, M. S. Hassan, M. S. Akhtar, C.-Y. Kim, J. M. Sohn, K.-J. Kim, H.-S. Shin, and O. B. Yang, Materials Letters 63, (2009) K.T. Song, J.Y.Lee, H.D.Kim, D.Y.Kim, S.Y.Kim, Synthetic metals 110, (2000) N. F. Mott, Journal of Non-Crystalline Solids 1, (1968) 1-17 TgTg TmTm PPy/SiC nanocomposites have higher thermal stability than that of pure PPy Nanorod is coated with the PPy