Transparent and highly liquid-repelling surfaces are interesting for a variety of applications such as fluidics, stain protection, and antifouling coatings. While much progress has been made in the field of water-repellent coatings, it remains challenging to obtain the same effect for liquids with low surface tension. This is particularly true for substrates with complicated morphologies.

Antonio Tricoli, The Australian National University, Canberra, Australia, and colleagues have produced highly transparent and superoleophobic coatings using the self-assembly of aerosol nanoparticles (NPs). Passing a SiO₂ NP aerosol over a substrate lead to the formation of NP assemblies with a re-entrant morphology, reminiscent of the structure of the broccoli plant. The superamphiphilic SiO₂ nanotextures were subsequently rendered superoleophobic by treatment with a fluorosilane precursor using chemical vapour deposition (CVD).

The resulting coatings were highly repellent against a wide range of low surface tension liquids, and the process could be applied to flexible and high-curvature substrates. According to the team, this process significantly advances the possibilities to confer superoleophobic properties onto otherwise not treatable substrates.

• Omnidirectional Self-Assembly of Transparent Superoleophobic Nanotextures,
  William S. Y. Wong, Guanyu Liu, Noushin Nasiri, Chonglei Hao, Zuankai Wang, Antonio Tricoli,
  ACS Nano 2017.
  DOI: 10.1021/acsnano.6b06715