Grafting PVDF Polymers and Polyimide-Based Polymers toward Improvement of Triboelectric Nanogenerator

Abstract

Triboelectric nanogenerators (TENGs), which can convert the mechanical energy (i.e., pressure, vibration, and friction) into the electricity using the coupling effects between triboelectrification and electrostatic induction, have been widely used as a representative means of energy harvesting. Despite significant progress in enhancing the output power of the TENGs, only few works have been investigated on the effect of newly synthesized insulating polymers on the high density of the charges that can be accumulated during physical contact. Herein, the polyvinylidene difluoride (PVDF)-grafted polymer and polyimide-based materials with different functionalities were synthesized for TENG applications to access the key factors determining the triboelectric characteristics. The PVDFgrafted polymers depending on the mole percent of grafting reagents onto the PVDF polymer, are systematically investigated with in-depth studies toward the relationship between their dielectric properties and performances on TENG. In addition, three copolymers bearing polyimide structures are made via a sequence of chemical imidization to induce their remarkable properties with imide-related functional groups in TENG with the increase of output for work functions. Furthermore, we synthesized the block copolymer based on polyimide to induce new properties, maintaining the existing properties. On the basis of these results, the trade-off system between the dielectric constants and work functions is demonstrated in this study to reveal the relationship between the insulator polymers and TENG.