Constructing multifunctional polyvinyl alcohol composite hydrogels with human-like skin properties using polyaniline-coated boron nitride nanofibers

Flexible conductive nanofibers play a crucial role in constructing hydrogels with human-like skin properties. However, it is still a challenge to construct flexible conductive nanofibers with good comprehensive properties. In this paper, we prepare composite fibers with excellent comprehensive properties by coating polyaniline (PANI) on the surface of flexible boron nitride nanofiber (BNNFs) template. BNNFs-PANI/PVA multifunctional composite hydrogels are created through the integration of BNNFs-PANI as nanofillers with soft poly (vinyl alcohol) (PVA) matrix using a one-pot self-assembly method. The composite hydrogels exhibit outstanding plasticity, self-adhesion, and self-healing properties, with a self-healing efficiency reaching up to 96% within 120 s. Furthermore, the tensile strength of the composite hydrogels has been enhanced by 36%, with the elongation at break exceeding 1500%. The compressive strength of the composite hydrogels at 60% strain is increased by 62%. Beyond these mechanical and self-healing features similar to human skin, the composite hydrogels also can serve as electronic pen for painting on a touchable electronic screen, simulating the function of human skin. Moreover, the dynamic changes in the abundant conductive network contribute to the composite hydrogels' high strain sensitivity. Compared with pure PVA hydrogels, it is improved by 29%. Notably, the strain sensitivity of the composite hydrogels is higher than that of most reported hydrogel sensors. Therefore, the composite hydrogels also can be employed as a real-time human motion sensor, capable of detecting and distinguishing various human movements. We believe that employing BNNFs as templates for crafting highly flexible and conductive nanofibers will foster the advancement of flexible conductive nanomaterials with comprehensive properties. Furthermore, the outstanding properties of the prepared composite hydrogels contribute to the ongoing development of conductive hydrogels with skin-like functionalities.