Functionalized thermoplastic polyurethane with tunable tribopolarity and biodegradability for high performance and biodegradable triboelectric nanogenerator

Triboelectric nanogenerators (TENGs) convert mechanical energy into electrical energy and have received considerable attention as a green energy technology to solve recently emerging global environmental issues. However, most high-power TENGs use polymers as active materials, which contributes to plastic pollution. Therefore, it is necessary to use eco-friendly and biodegradable materials while maintaining high output performance for further development of TENGs as a next-generation green energy technology. This study designs a biodegradable thermoplastic polyurethane (TPU) based on polycaprolactone diol. The TPU was modified using polydimethylsiloxane diol and a chain extender containing fluorine units, which controlled the modification, output performance, and biodegradability of the TENG. Biodegradability varies depending on the structure of the TPU, especially the chain extender. The output of the TENG fabricated based on the modified TPU was considerably increased with a voltage from 1.31 V to 74.03 V and current from 0.02 μA to 1.98 μA. Further, the maximum power density increased approximately 1423 times compared to that of the native TPU-based TENG to a value of 42.71 μW/cm2. This study provides a potential strategy for the development of environmentally friendly, high-powered next-generation TENGs by ensuring controlled biodegradability.