Polymer composites with lychee-like core covered by segregated conducting and flexible networks: unique morphology, high flexibility, stretchability and thermoelectric performance

Polymer nanocomposites show great potential as platforms for the development of organic synthetic devices and systems, while a rational structural design of the matrix and the precursors are still urgently needed to ensure the viable development of these composite materials. Here, we report the controlled preparation of the novel composites with lychee-like polymer core covered by carbon nanotube/polyurethane segregated conducting and flexible networks. The composites were fabricated using a simple aqueous coating strategy. The resultant self-supporting films showed outstanding flexibility and stretchability with the minimum bending radius of less than 1 mm and an elongation at break of 3.8%. In addition, the composite films exhibited excellent thermoelectric function with the electrical conductivity, Seebeck coefficient, and power factor of 109.3 ± 4.3 S cm−1, 24.0 ± 0.2 μV K−1, and 6.28 ± 0.52 μW m−1 K−2, respectively.