Unveiling the synergistic mechanism of C-F and C-Cl bonds in enhancing the triboelectric performance of fluorinated polymers

Achieving superior tribo-negative performance beyond traditional fluorinated polymers (TFPs) is crucial for advancing triboelectric devices. In this work, we identified an approach to enhance the tribo-negative properties of TFPs via synergistic effects of C-F and C-Cl bonds, based on the significant tribo-differences observed in polyvinylidene fluoride (PVDF) based copolymers. Our findings indicate that the -CTFE unit, particularly its C-Cl bond, significantly lowers the LUMO of the copolymer system, resulting in PVDF-CTFE (PC) exhibiting the strongest tribo-negative properties. By controlling the surface Cl/F ratio via chlorine plasma treatment, it was demonstrated that a higher C-Cl content enhances electron acquisition, whereas a higher C-F content improves charge retention. The synergistic effect optimally balances triboelectric charge capture and losses, enabling PC-Cl to achieve the highest triboelectric charge density (310 µC cm-2) among PVDF copolymers. Our results will provide a versatile strategy for enhancing a wide range of tribo-negative materials.