For many centuries people have pondered how some materials become electrically charged when compresses, rubbed, or just brought into contact with other, dissimilar materials. We now know that this charging phenomena is governed either by piezoelectricity (from deformation) for materials with non-centrosymmetric unit cells, or contact electrification (also known as triboelectricity, from interfacial friction). While piezoelectricity (and ferroelectricity) is well understood, the mechanisms of contact electrification - particularly for dielectric polymers - remain a subject of debate in literature.[1] This debate, on the driving force being electron-, ion-, and/or material-transfer [2,3] coupled to poor measurement techniques has led to the conflation of piezoelectric and contact electrification effects significantly hindering the development of optimal polymer energy harvesters.[3]
In this talk, I highlight our efforts to develop a clear understanding of contact electrification, from measurement techniques through to mechanisms – simply by considering their interfaces. We have shown that charging polarity can be directly determined simply by knowing the cohesive energy density of the polymers [4] and their relative surface roughness.[5] These relatively simple understandings have enabled the production of triboelectric laminates assemblies from arbitrary polymers, [6-8] which can equal or outperform piezoelectric fluoropolymers. Moving forwards, these laminates (as well as piezoelectric polymers), are being studied as tools to drive catalytic reactions ranging from fuel production to small molecule synthesis.
References:
[1] D. J. Lacks, et al., Nature Reviews Chemistry 2019, 10.1038/s41570-019-0115-1; [2] O. Verners, et al., Advanced Materials Interfaces 2023, 10.1002/admi.202300562; [3] A. Šutka, et al., Advanced Materials Interfaces 2023, 10.1002/admi.202300323; [4] P. C. Sherrell, et al., ACS Applied Materials & Interfaces 2021, 10.1021/acsami.1c13100; [5] O. Verners, et al., Nano Energy 2022, 10.1016/j.nanoen.2022.107914; [6] P. C. Sherrell, et al., Small 2024, 10.1002/smll.202311570; [7] A. Šutka, et al., Advanced Energy and Sustainability Research 2024, 10.1002/aesr.202300259; [8] A. Linarts, et al., Small 2023, 10.1002/smll.202205563