Sprecher
Beschreibung
Substrates with switchable or adjustable wetting properties are desirable for actuators, coatings, filters or biomedical applications. In this work we present a study of two different substrates. Firstly, the possibilities of an electrically conductive polymer, i.e., polypyrrol in combination with porous silicon are explored, where previous studies already showed how an electric field can influence the chemo-mechanical properties of the polymer [1, 2] and the Young contact angle [3]. Secondly, we analyze the wetting and fluid transport properties of an alumina inverse opal structure (Al2O3), which undergoes a spontaneous transition under ambient condition to a more hydrophobic state in time. This transition can be reversed by a low temperature heat treatment. While, a high-temperature heat treatment irreversibly change the porous network structure [4], the low-temperature treatment preserves the inverse opal original structure.
[1] Kaneto, K., Sonoda, Y., & Takashima, W. (2000). Direct measurement and mechanism of electro-chemomechanical expansion and contraction in polypyrrole films. Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 39(10), 5918–5922.
[2] Brinker, M., Dittrich, G., Richert, C., Lakner, P., Krekeler, T., Keller, T. F., ... & Huber, P. (2020). Giant electrochemical actuation in a nanoporous silicon-polypyrrole hybrid material. Science advances, 6(40), eaba1483.
[3] Chang, J. H., & Hunter, I. W. (2011). A superhydrophobic to superhydrophilic in situ wettability switch of microstructured polypyrrole surfaces. Macromolecular Rapid Communications, 32(9–10), 718–723.
[4] Furlan, K. P., Pasquarelli, R. M., Krekeler, T., Ritter, M., Zierold, R., Nielsch, K., Schneider, G. A., & Janssen, R. (2017). Highly porous α-Al2O3 ceramics obtained by sintering atomic layer deposited inverse opals. Ceramics International, 43(14), 11260–11264.