In this study, different morphologies of polyaniline (PAni) nanostructures were obtained via interfacial polymerization. The influence of the time and temperature of polymerization on morphology was investigated. At room temperature the growth of nanosheets and nanoflowers with long polymerization time (1-5 days) was observed. In the syntheses carried out at 50°C the same nanostructures were obtained with only a few hours of polymerization, which illustrates that the increase in temperature considerably reduced the synthesis time and also provided the growth of nanofibers, morphology not found in the syntheses performed at room temperature. The characterization by XRD indicated the presence of diffraction peaks characteristic of PAni nanostructures with high crystallinity. As the conductivity of PAni is directly related to its crystallinity, it is expected that the nanostructures obtained have high conductivity, which may represent a greater potential for diverse applications. It can be concluded that the proposed synthesis presents a simple alternative for obtaining PAni nanostructures with different morphologies and high crystallinity.

In this work, nanocomposite films of indium tin oxide (ITO) nanowires in a PMMA matrix were obtained by tape casting. The electrical, optical and morphological properties of films were studied as a function of the amount of wires inserted in the composite, and it was used 1, 2, 5, and 10 wt %. Results confirmed that films transmittance decreases as the concentration of wires increases, attaining a minimum transmittance of 55% for 10 wt % of filler. On the other hand, the electrical resistance of composites was found to decrease by increasing the filler amount and the dc characterization indicate that percolation occurs for about 5 wt % of wires. The morphological studies carried out by TEM were considered to be in good agreement with the electrical results and confirm that for 5% of filler, the ITO nanostructures are in contact with one another inside the polymer. Moreover, we made computational simulation of 1D structures in a general matrix and it was found that percolation should occur for about 12 wt %. Although computational results indicate higher amount of wires necessary for percolation than we found experimentally, both results illustrate that using one-dimensional nanostructures as filler in composites enables obtaining percolation for a smaller amount of filler than when using, for instance, nanoparticles. Therefore, the simple processing technique employed here can be used to obtain transparent and conductive composites with several useful applications.

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Composite films made of poly(vinylidene fluoride) (PVDF) and conducting particles of carbon black (CB) were prepared using a hot press. Using different volume fractions of CB filler, electrical properties of the samples were analyzed with current-voltage (I 9 V) measurements and impedance spectroscopy. To help the discussion, percolation theory and simulation circuits based on Colie diagrams were used. The percolation threshold was found at 3 vol% of CB. At these volume fractions of filler, scanning electron microscopy (SEM) images showed connected particles in the polymer matrix, while in the higher volume content of filler, the particles started to form clusters. Furthermore, it was observed that increasing volume fractions up to 3 vol%, the Young's modulus and the tensile strength of the composite film were higher than that of the pure polymer, although the rupture strain was decreased. Composite films with 3 vol% of CB showed optimized electrical and mechanical properties and may be useful as an electrostatic dissipater.