Flexible conductive nanocomposites with the ability of self‐assembly into well‐ordered structures are promising multifunctional materials for energy conversion and storage devices. In this work, flexible nanocomposites based on multi‐walled carbon nanotubes (MWCNTs) and poly(styrene‐butadiene‐styrene) (SBS) were obtained by solution casting, followed by a post‐annealing treatment, during 7 days at 110 °C, to enable the self‐organization of the SBS. The impact of the MWCNTs on the self‐assembly was studied by atomic force microscopy and Small angle X‐rays scattering, and the conductivity of these nanocomposites was analyzed over the broadband frequency range, that is, 10−1–106 Hz. The results revealed that the lower MWCNTs loadings (∼0.2 v %) were the most suitable to achieve a conductive network through the SBS, maintaining self‐assembled domains. These domains include hexagonally packed cylinders and alternating lamellae. Furthermore, at loadings above 1 v %, the impact of further MWCNTs addition on the conductivity was marginal over the whole frequency range and the self‐assembly tendency was progressively reduced. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46650.

Multiferroics are an important family of materials with special properties suitable for applications in advanced technological devices. In most of the cases, the ferroelectric ordering and domain wall formation determine and control their operation and functionality. However, the physical mechanisms by which these domain walls are formed are still not yet completely clarified. Also, in the last few years, few advances are found in the mechanisms used to explain the domain walls and their influence on the materials properties. In this work, the domain walls in ferroelectric multiferroics were investigated by using high-resolution transmission electron microscopy and image simulations. The ferroelectric switching was also observed by piezoresponse force microscopy. A three-dimensional atomic-level framework of 90 ferroelectric domain walls was proposed and the structural and ferroelectric features at the domain walls, such as length, width, and angle between domains, were determined. From these studies, it was found that ferroelectric and structural features of multiferroic BiFeO 3 -PbTiO 3 compounds, such as domain-orientation, electrical conductivity, magnetic ordering, and brittleness due to strains at the domain walls, can be controlled by particular atomic substitutions at the A site of the perovskite structure.

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Ferroelectric domain walls are modeled as rigid bodies moving under the action of a potential field in a dissipative medium. Assuming that the dielectric permittivity follows the dependence ε′∝1/(α+βE2), it obtained the exact expression for the effective potential. Simulations of polarization current correctly predict a power law. Such results could be valuable in the study of domain wall kinetic and ultrafast polarization processes. The model is extended to poled samples allowing the study of nonlinear dielectric permittivity under subswitching electric fields. Experimental nonlinear data from PZT 20/80 thin films and Fe+3 doped PZT 40/60 ceramic are reproduced.