Poly[(Butyl acrylate)- co-(butyl methacrylate)] as Transparent Tribopositive Material for High-Performance Hydrogel-Based Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) with high-energy output and high flexibility and transparency are desirable for a number of applications including flexible and transparent wearable devices. The output power of triboelectric nanogenerators (TENGs) relies on the triboelectric property of tribomaterials. However, the available choice of transparent elastomeric tribopositive materials is very limited. In this study, a poly[(butyl acrylate)-co-(butyl methacrylate)] (PBA-PBMA) block copolymer was synthesized and used as a tribopositive material for TENGs. The synthesized PBA-PBMA copolymer has an ultrahigh molecular weight, high transparency, and high elasticity. A hydrogel-based dual-electrode TENG (HDTENG) was developed using PBA-PBMA copolymer and polydimethylsiloxane (PDMS) as the tribopositive and tribonegative layers, respectively, and sodium chloride containing polyacrylamide (PAM) hydrogels were used as electrodes. The HDTENG possesses high flexibility, moderate transparency (∼58% transmittance), and an extraordinary triboelectric output performance. A high open-circuit voltage of ∼280 V and short-circuit current of ∼34 μA were achieved by the HDTENG, and a peak power density of 1.1 W/m2 was reached at an external resistance of 4.7 Mω. After converting the alternating current to direct current using a bridge rectifier, the energy generated by the HDTENG can be used to light up 240 blue and green LEDs and power various electronics, including a pedometer, digital timer, and swimming watch. The HDTENG also showed the capability to sense human motion, such as arm bending.