Effectively altering the triboelectric charging behavior of chitosan films via tannic acid surface modification

Variations in triboelectric charging behavior significantly influence the performance of triboelectric nanogenerators, including shifts in triboelectric polarity. However, research on biopolymers with respect to these characteristics remains limited, creating a knowledge gap in the understanding of triboelectricity and restricting material options. In this study, a novel strategy is proposed for altering the triboelectric charging behavior of chitosan films through tannic acid (TA) surface modification. The galloyl groups of TA interact with the -NH₂ groups that serve as electron-donating sites, and the aromatic structure within galloyl groups further modifies the surface properties, shifting triboelectric polarity from positive towards relatively negative. The modified chitosan film with 10 % TA concentration reached a charge density of 182 μC m⁻² and demonstrated exceptional mechanical properties, including a tensile strength of 55.8 MPa. It also exhibited enhanced moisture resistance with a water solubility of just 12.8 %, and showed 96.5 % inhibition efficiency against S. aureus at 256 μg mL⁻¹. These features make it an excellent candidate for biomedical applications. Additionally, a potential application of charge manipulation to enhance the fluffiness of down was further developed. This work presents a promising approach to modify the triboelectric charging behavior of chitosan and broaden its partner material options.