Uncontrollable wetting and contamination of surfaces with fluids and the therein dissolved substances can be detrimental for many applications in different sectors. Repellent and self-cleaning coatings offer a promising solution, such as anti-biofouling [1,2], anti-corrosion [2,3] or medical surfaces (for example, to prevent blood coagulation) [4]. An artificial self-cleaning surface is usually realized by the lotus effect. Here, low adhesion of water droplets and the contained contaminants is achieved by minimizing the contact area. Another bioinspiration for repellent surface coatings is the pitcher plant. Confining a suitable lubricant to porous surface structures by matching the surface chemistry prevents the direct contact of a contaminating liquid containing for example micro- or macro-organisms with the solid surface. [5,6] Due to complicated multi-step processes and expensive equipment, most of the methods developed so far are limited to laboratory scale and are not scalable to industrial applications. Additionally, many techniques are toxic to the environment due to the chemicals used, i.e., aggressive organic solvents or undesirable perfluorinated substances [7,8,9].

Our different methods to produce such self-cleaning surfaces however are environmentally friendly and due to its application via spray-coating potentially scalable to industrial purposes. We work predominately water-based and at room temperature. Therefore, we avoid high temperatures and high amounts of organic solvents. Switching the used binder as well as the lubricant to renewable resources additionally increases the sustainability. In promising tests against biofouling, we identified a first potential application field.

References

[1] S.M.R. Razavi, et al., ACS Sustainable Chem. Eng., 2019, 7, 14509-14520.

[2] E.-C. Cho, et al., Chem. Eng. Journal, 2017, 314, 347-357.

[3] E. Vazirinasab, et al., Surf. Coatings Technol., 2018, 341, 40–56.

[4] V. Jokinen, et al., Adv. Mater., 2018, 30, 1705104.

[5] M. Villegas, et al., ACS Nano, 2019, 13, 8517-8536.

[6] N. Vogel, et al., Nature Communications, 2013, 4, 2176.

[7] R. van Zelm, et al., Environ. Toxicol. Chem., 2008, 27, 2216-2223.

[8} M.J.A. Dinglasan, et al., Environ. Sci. Technol., 2004, 38, 2857-2864.

[9] L. Xu., et al., ACS Appl. Mater. Interfaces, 2014, 6, 9029-9035.