Robust Nanogenerators Based on Tribo-Positive Graft Copolymers of Tribo-Negative Poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) and its copolymers are useful for a diverse range of applications in energy production and storage, sensors, actuators, separator, and filter membranes. Herein, we report on the single-step transformation of electroactive tribo-negative pristine PVDF into tribo-positive PVDF copolymer (G-PVDF) by grafting poly(diethylene glycol methyl ether methacrylate) on the backbone by a coupled atom-transfer radical polymerization protocol. The resultant G-PVDF with rough spherulitic morphology is utilized to fabricate a triboelectric nanogenerator (G-TENG) using the combination of tribo-negative polydimethylsiloxane as active materials. Highly robust G-TENG generates a peak-to-peak voltage of ∼1050 V under open-circuit condition and an output current density of 31.25 × 10 –2 A m –2 equivalent to an output power density of 56.25 W m –2 . Furthermore, the application of the G-TENG as a realistic portable electrical power source is shown by powering over 400 market-available red light-emitting diodes and liquid crystal displays. The G-TENG shows mechanical stability over 9500 cycles and ambient stability over 150 days. Parallel to the scavenging of electrical energy from mechanical energy, we demonstrate the use of G-TENG for flexible self-powered health care applications. The synthesis of tribo-positive G-PVDF copolymer as a green energy-harvesting material has great potential for a variety of applications considering the versatile use of pristine PVDF.