Role of Mechanical Properties in the Triboelectric Behavior of Polymers for Wearable Triboelectric Nanogenerators

Wearable triboelectric nanogenerators need to meet both the triboelectric output and flexibility requirements of wearable devices, which narrow down the material choices. The complexity in the selection of candidate materials is linked to the interdependence between mechanical properties and triboelectric behavior, made even more evident when two chemically identical and mechanically dissimilar materials result in significant triboelectric output when contacted. In order to comprehensively understand the role of mechanical properties in the triboelectric behavior of chemically identical materials, we designed an experimental framework to examine the effect of mechanical properties on the triboelectric output of polymers using polydimethylsiloxane (PDMS) as a model material. By maintaining the chemical composition and microscale surface roughness of the PDMS samples constant while varying the base-to-curing agent mixing ratio and thermal history, this study isolated the effects of mechanical properties. It is found that the mechanical behavior of the triboelectric material affects both the triboelectric charges generated at the contact surface and the charges accumulated at the interface between the material and the electrode, which results in deep richness and complexity to the material space selection and the triboelectric nanogenerator device design. This study sheds light on the role of mechanical properties in the triboelectric behavior of polymers and contributes to material selection and the development of wearable triboelectric nanogenerators.