TY - JOUR
T1 - Imaging the air-water interface
T2 - Characterising biomimetic and natural hydrophobic surfaces using in situ atomic force microscopy
AU - Elbourne, Aaron
AU - Dupont, Madeleine F.
AU - Collett, Simon
AU - Truong, Vi Khanh
AU - Xu, Xiu Mei
AU - Vrancken, Nandi
AU - Baulin, Vladimir
AU - Ivanova, Elena P.
AU - Crawford, Russell J.
PY - 2019/2/15
Y1 - 2019/2/15
N2 - The interface between water and a textured hydrophobic surface can exist in two regimes; either the Wenzel (surface-engulfed) or Cassie-Baxter (water-suspended) state. Better understanding of the influence of pattern geometry and spacing is crucial for the design of functional (super)hydrophobic surfaces, as inspired by numerous examples in nature. In this work, we have employed amplitude modulated – atomic force microscopy to visualize the air-water interface with an unprecedented degree of clarity on a superhydrophobic and a highly hydrophobic nanostructured surface. The images obtained provide the first real-time experimental visualization of the Cassie-Baxter wetting on the surface of biomimetic silicon nanopillars and a naturally superhydrophobic cicada wing. For both surfaces, the air-water interface was found to be remarkably well-defined, revealing a distinctly nanostructured air-water interface in the interstitial spacing. The degree of interfacial texture differed as a function of surface geometry. These results reveal that the air-water interface is heterogeneous in its structure and confirmed the presence of short–range interfacial ordering. Additionally, the overpressure values for each point on the interface were calculated, quantifying the difference in wetting behavior for the biomimetic and natural surface. Results suggest that highly-ordered, closely spaced nanofeatures facilitate robust Cassie-Baxter wetting states and therefore, can enhance the stability of (super)hydrophobic surfaces.
AB - The interface between water and a textured hydrophobic surface can exist in two regimes; either the Wenzel (surface-engulfed) or Cassie-Baxter (water-suspended) state. Better understanding of the influence of pattern geometry and spacing is crucial for the design of functional (super)hydrophobic surfaces, as inspired by numerous examples in nature. In this work, we have employed amplitude modulated – atomic force microscopy to visualize the air-water interface with an unprecedented degree of clarity on a superhydrophobic and a highly hydrophobic nanostructured surface. The images obtained provide the first real-time experimental visualization of the Cassie-Baxter wetting on the surface of biomimetic silicon nanopillars and a naturally superhydrophobic cicada wing. For both surfaces, the air-water interface was found to be remarkably well-defined, revealing a distinctly nanostructured air-water interface in the interstitial spacing. The degree of interfacial texture differed as a function of surface geometry. These results reveal that the air-water interface is heterogeneous in its structure and confirmed the presence of short–range interfacial ordering. Additionally, the overpressure values for each point on the interface were calculated, quantifying the difference in wetting behavior for the biomimetic and natural surface. Results suggest that highly-ordered, closely spaced nanofeatures facilitate robust Cassie-Baxter wetting states and therefore, can enhance the stability of (super)hydrophobic surfaces.
KW - Air-water interface
KW - Hydrophobicity
KW - Nanomaterials
KW - Nanostructured surfaces
KW - Superhydrophobicity
UR - http://www.scopus.com/inward/record.url?scp=85055666821&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/ARC/IH130100017
U2 - 10.1016/j.jcis.2018.10.059
DO - 10.1016/j.jcis.2018.10.059
M3 - Article
C2 - 30380435
AN - SCOPUS:85055666821
SN - 0021-9797
VL - 536
SP - 363
EP - 371
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
ER -