Harvesting Motion via Polymers: From Mechanisms to Electricity

For many centuries people have pondered (notably and dubiously Thales of Miletus)^[1] why some materials become electrically charged when brought into contact with other, dissimilar, materials. We now know that this charging phenomena is governed either by piezoelectricity from deformation, for 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 remain a subject of debate in the literature.^[2] This debate on the driving force being electron-, ion-, or material-transfer,^[2-3] coupled to poor measurement techniques leading to conflation of piezoelectric and contact electrification,^[4-5] has limited the design of optimal polymer energy harvesters.

If we can develop improved understandings of how polymers charge from friction, we can design devices that can capture motion to harvest electricity,^[6] drive chemical reactions,^[7] or even enable wound healing.^[8]

To address this lack of understanding, we have studied how polymers generate charge at a contact interface. This has linked the polarity of generated charge directly to polymer structure via cohesive energy density,^[9] and surface topography.^[10] These relatively simple understandings have enabled the production of layer-by-layer ‘laminate’ assemblies from arbitrary polymers.^[11] These laminates, which function purely off contact electrification and interfacial friction, generate internal dipole moments that mimic piezoelectric polymers – enabling exceptionally efficient vibrational energy harvesting. Finally, we demonstrate the use of recycled foamed/expanded polystyrene to fabricate such laminates, capable of harvesting over 12 µA and 200 V from just 16 N of force. Moving forwards, these laminates, as well as piezoelectric polymers,^[12] are being studied tools to drive catalytic reactions ranging from fuel production through to small molecule synthesis.

This talk aims to provide a pathway to design highly efficient electromechanically active surfaces from polymers towards catalysis and sustainable chemistry.

References:
[1] P. Iversen, et al., Journal of Electrostatics 2012, 70, 309, 10.1016/j.elstat.2012.03.002
[2] D. J. Lacks, et al., Nature Reviews Chemistry 2019, 3, 465, 10.1038/s41570-019-0115-1
[3] A. Šutka, et al., Advanced Materials Interfaces 2023, n/a, 2300323, 10.1002/admi.202300323
[4] R. T. Leon, et al., Nano Energy 2023, 110, 108445, 10.1016/j.nanoen.2023.108445
[5] A. Šutka, et al., Adv. Mater. 2020, 32, 2002979, 10.1002/adma.202002979
[6] A. Šutka, et al., ACS Applied Energy Materials 2023, 10.1021/acsaem.3c01196
[7] J. Zhang, et al., Journal of the American Chemical Society 2021, 143, 3019, 10.1021/jacs.0c11006
[8] F.-C. Kao, et al., Science and Technology of Advanced Materials 2022, 23, 1, 10.1080/14686996.2021.2015249
[9] P. C. Sherrell, et al., ACS Applied Materials & Interfaces 2021, 13, 44935, 10.1021/acsami.1c13100
[10] O. Verners, et al., Nano Energy 2022, 104, 107914, 10.1016/j.nanoen.2022.107914
[11] A. Linarts, et al., Small 2023, 19, 2205563, 10.1002/smll.202205563
[12] N. A. Shepelin, et al., Nature Communications 2021, 12, 3171, 10.1038/s41467-021-23341-3