Waterborne fluoropolymer dispersions for (super)hydrophobic coatings

Abstract

This work focused on the development of hydrophobic (¿water > 90¿) and superhydrophobic coatings (¿water > 150¿) to be applied to large complex surfaces in high performance applications where excellent water repellency is required. An important requirement is that the developed materials need to be applied to large surfaces by conventional coating methods such as brushing or spraying to make viable their commercial utilization. The production of these materials in water media instead of solvent media in order to reduce VOCs is particularly valuable and challenging. Waterborne dispersions from fluorinated polymers were produced by miniemulsion polymerization. Fluoropolymers are highly hydrophobic and additionally, they provide a large number of benefits to the final coating such as improved weatherability, corrosion resistance or easy to clean properties. The key aspects of this work include the synthesis of different water-based fluoropolymers and the attempts to fine-tune the film surface topography by several methods to increase hydrophobicity. Highly hydrophobic coatings were obtained by blending different fluorinated homo and copolymers (¿water ¿ 137¿) and also by controlling the film topography to promote the formation of wrinkles on the film surface (¿water ¿ 133¿). Additionally, the superhydrophobic regime (¿water > 150¿) was achieved by a dual coating strategy where a dispersion that led to highly rough fluoropolymer microstructures was sprayed on the surface of a film forming polymer during the open time. Finally, the incorporation of the waterborne fluoropolymers previously synthesized in a commercial paint formulation and the analysis of the properties of the final paints were also studied showing an interesting matting effect, excellent chemical resistance and potential to reduce VOCs.