To meet the demands of multifunctional applications, developing functional composites with excellent properties (such as high dielectric permittivity, good mechanical properties, and anisotropic optical transmittance) is urgent. In this regard, preparing composites with all‐organic components is a promising strategy. Herein, we demonstrated a simple and time‐saving method for assembling and aligning polyaniline (PANI) particles in the TPU matrix by an AC electric field. The alignment of PANI in the polymer matrix not only obviously enhances dielectric permittivity but also effectively increases optical anisotropy. At the same filler loading content, the dielectric permittivity of aligned composites prepared under 10 Hz electric fields is 10.63 (10−1 Hz), which is higher than the dielectric property of random composites (8.58). The kinetics of aligning process of PANI particles are systematically studied by in situ optical microscope while an AC electric field is applied. We believe that this research work provides a potential solution to increase both dielectric permittivity and optical anisotropy of composites by the alignment of organic fillers via an electric field, which is essential for future flexible wearable electronics.

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Polymer-based composite films with multiple properties, such as low dielectric loss tangent, high dielectric constant, and low cost are promising materials in the area of electronics and electric industries. In this study, flexible dielectric films were fabricated via an electric field-assisted method. Polyaniline (PANI) was modified by polyvinylpyrrolidone (PVP) to form a core–shell structure to serve as functional particles and silicone rubber polydimethylsiloxane (PDMS) served as the matrix. The dielectric constant of the composites prepared under electric fields was improved by the micro-structures formed by external electric fields. With the addition of 2.5 wt% PVP@PANI, the dielectric constant could be significantly enhanced, up to 23; the dielectric loss tangent is only 1, which is lower than that of the aligned PANI samples. This new processing technology provides important insights for aligning fillers in polymer matrix to form composites with enhanced dielectric properties.