Thin Film Formulations
Bioinspired surfaces of special wetting properties, from superhydrophobicity to superhydrophilicity and superoleophobicity to superoleophilicity, have attracted considerable attention because of their numerous potential applications.
Superhydrophobicity, accompanied by water repellency, is usually achieved by developing the special hierarchical micrometer and nanometer sized structure of the lotus leaf on the surface of interest and applying low surface energy agents.
Superomniphobic surfaces repel not only water, but virtually any liquid thrown on them. For practical applications, however, attention is mainly focused on oil and water repellency. The development of strategies to produce superomniphobic surfaces can be considered as the natural sequence of more than twenty years of research on superhydrophobic surfaces. On the basis of these principles, and in relation to the final product application, several methods have been developed the last twenty years to fabricate superhydrophobic surfaces such as lithographic patterning, chemical vapour deposition, sol-gel process, and controlled nanoparticle embedding into polymer matrices.
Our researchers have been working into the field of superhydrophobic, superoleophobic and ombiphobic coatings for over a decade via the sol-gel methodology as well as the controlled nanoparticle embedding into polymer matrices. The latter has the advantage that it is an easy process of low cost as it can be implemented using common (materials) polymers, nanoparticles and solvents.
With proper combination of nanoparticles and hydrophobic polymers, it is possible to produce superhydrophobic coatings achieving large static contact angles (θS>150o) of water drops. The superhydrophobic surfaces of these coatings incorporate roughness on both micron and nanometer length scales originating from the filler nanoparticle clusters.
The large θS (>150°) may be accompanied by low tilt angle (θt) implying water repellency, that is water drops can effortlessly roll off the surface, like they do on the surface of the lotus leaf (lotus effect).
Untreated sample
Treated sample
Self/easy cleaning properties of silk covered by siloxane enriched with 2% w/w SiO2 nanoparticles. The easy removal of soil by water droplets is demonstrated in (a). The mechanical removal of wax is shown in (b) for untreated and treated (siloxane+2% w/w SiO2) silk.
Our formulations have been applied in different substrates, such as building materials, metallic surfaces and textiles.
