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The effects of the thermoelastic and piezoelectric strain exerted by an active polymer matrix on a Ni nanowire (NW) are studied at the nanoscale by measuring the inverse magnetostriction of single-contacted Ni NWs. The reorientation of the magnetization is measured by anisotropic magnetoresitance. In the absence of strain, the Ni NW exhibits a typical uniform rotation of the magnetization as a function of the external field. When piezoelectric or ther-moelelastic strain is present in the polymer matrix, the hysteresis loop becomes strongly modified by the inverse magnetostriction of Ni. It is shown that the ferromagnetic NW plays then the role of a mechanical probe that allows the effects of the mechanical strain to be characterized and described qualitatively and quantitatively. Moreover the stress exerted by the polycarbonate matrix on the NW is found to be isotropic while the one produced by the PVDF matrix is anisotropic.

Surface conductive composites consisting of polyamide 6 (PA-6) polymer films and conductive polyaniline (PANI) particles were chemically elaborated by in situ polymerization of aniline inside the PA-6 matrix, at room temperature. The obtained composites were investigated regarding to their electrical properties. We have measured the frequency dependence of permittivity of these antistatic polymer films (ASPF). Surface conductivity was also characterized using potential decay technique. The enhanced surface conductivity was due to percolation of PANI phase in the surface layer of PA-6 films.

A new approach to explain the interfacial polarization phenomenon in conducting composite films is proposed. HCl-doped poly(ethylene terephthalate) (PET) and polyamide-6 (PA-6) matrices with embedded polyaniline (PANI) particles as filler were investigated and analysed, combining dielectric spectroscopy and AFM electrical images with the effective medium theory analysis. Up to three relaxation peaks attributed to the interfacial polarization phenomena were detected in the studied frequency range (0.1 Hz–1 MHz). The AFM electrical images revealed that the doped PA-6/PANI composite can be modelled as a single-type particle medium and the PET/PANI one as a two-type particle medium. A simple dielectric loss expression was derived from the Maxwell–Wagner–Hanai mixture equation and was applied to the experimental data to identify the interfaces involved in each of the relaxation peaks. The parameter values (permittivity, conductivity, volume fraction of the PANI particles) were found to agree well with the measured one, hence validating the models.