Keynote lecture. Biomimetic, nanostructured coatings: superhydrophobic performances and applications (Comunicazione a convegno)

Type
Label
  • Keynote lecture. Biomimetic, nanostructured coatings: superhydrophobic performances and applications (Comunicazione a convegno) (literal)
Anno
  • 2013-01-01T00:00:00+01:00 (literal)
Alternative label
  • Mariarosa Raimondo (2013)
    Keynote lecture. Biomimetic, nanostructured coatings: superhydrophobic performances and applications
    in XIII European Ceramic Conference, Limoges (France), 23-37 June 2013
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Mariarosa Raimondo (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Institute of Science and Technology for Ceramics, ISTEC CNR (literal)
Titolo
  • Keynote lecture. Biomimetic, nanostructured coatings: superhydrophobic performances and applications (literal)
Abstract
  • Wettability is a fundamental property of a solid surface, whose control plays an important role in many different industrial sectors: from ceramics to the aerospace, naval or maritime applications, to electronics devices, pipelines and so on. In last years, a lot of studies have focused on mimicking the high ability to repel water or other non-polar fluids such oils, which can be found in nature, trying to replicate it on synthetic materials. This concept takes inspiration from the hierarchical structure shown by various living organisms (i.e Lotus leaf, gecko, etc) that relies on a combination of surface morphology and chemistry to repel water and/or oils from their surface. Synthetic, super-hydrophobic surfaces with a dramatically improved repellence to water and great application potential should present static contact angle with water higher than 150° in order to exhibit enhanced self-cleaning attitudes. However, current knowledge suggests that surfaces with low contact angle hysteresis - defined as the difference between the advancing and receding contact angle in dynamic sliding movements of a fluid drop - are required to solve or reduce ice or fouling adhesion in materials withstanding adverse environmental conditions. In addition, design techniques coupling static and dynamic super-hydrophobicity with repellence to oils (termed as \"amphiphobic\" behaviour) would be extremely relevant to extend the application fields of many products. In this work, different typologies of materials - ceramics, metals, alloys - were processed in order to get special wettability of their surfaces by means of chemical and microstructural modifications at the nano-scale: functional top layers, made up of thin, hybrid coatings and deposited by dip coating, provided materials with extreme repellence to water from both the static and dynamic point of view. By this way, optically transparent, homogeneous, nanostructured organic/inorganic hybrid coatings, with a thickness in the 200-300 nm range, have been generated by sol-gel method (particle dimensions of about 30 nm), followed by thermal processing and application of low energy elements, such as fluorine. Static contact angles with water as high as 178 ± 1° were obtained on ceramic tile, aluminium and alloys, the same materials presenting excellent dewetting phenomena, as certified by the contact angle hysteresis lower than 5 ± 1°. A good repellence against low surface tension fluids (oils) was also obtained. This result represents a significant improvement beyond the current state-of-the-art concerning amphiphobic products. Thin coatings were tested in order to investigate their mechanical resistance and durability to wearing phenomena, their anti-frost performances and resistance to chemical attacks. Up today, these results encourage to think that a new class of materials can be developed and scaled up to different industrial applications. (literal)
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