Hierarchically structured superhydrophobic coatings fabricated by successive Langmuir–Blodgett deposition of micro-/nano-sized particles and surface silanization

Abstract

The present study demonstrates the creation of a stable, superhydrophobic surface by coupling of successive Langmuir-Blodgett (LB) depositions of micro- and nano-sized (1.5 µm/50 nm, 1.0 µm/50 nm, and 0.5 µm/50 nm) silica particles on a glass substrate with the formation of a self-assembled monolayer of dodecyltrichlorosilane on the surface of the particulate film. Particulate films, in which one layer of 50 nm particles was deposited over one to five sublayers of larger micro-sized particles, with hierarchical surface roughness and superhydrophobicity, were successfully fabricated. Furthermore, the present 'two-scale' (micro- and nano-sized particles) approach is superior to the previous 'one-scale' (micro-sized particles) approach in that both higher advancing contact angle and lower contact angle hysteresis can be realized. Experimental results revealed that the superhydrophobicity exhibited by as-fabricated particulate films with different sublayer particle diameters increases in the order of 0.5 µm>1.0 µm>1.5 µm. However, no clear trend between sublayer number and surface superhydrophobicity could be discerned. An explanation of superhydrophobicity based on the surface roughness introduced by two-scale particles is also proposed.

Superhydrophobicity: Cavity growth and wetting transition

“…37 Many studies report various methods on how to prepare superhydrophobic surfaces. [38][39][40][41] The surfaces do not only exhibit the obvious water repellent properties but can also work as corrosion protection, 42,43 anti-icing coatings, [44][45][46] protection of electrical components 47 and extreme water resistance of papers 48 and fabrics. 49 Another aspect of industrial importance is the influence on adhesion and friction properties.…”

Highly Stretchable Superhydrophobic Composite Coating Based on Self‐Adaptive Deformation of Hierarchical Structures

“…Superhydrophobic surfaces with a water contact angle (CA) higher than 150° and a sliding angle (SA) lower than 10°, which exist in nature (e.g., lotus leaves and butterfly wings), have a wide application in self‐cleaning, water‐proofing, anti‐icing, and anticorrosion . The water repellency of such surfaces often depends on low‐surface‐energy components and proper roughness created by micro and nanoscale structures . Among two, the roughness plays a more important role in superhydrophobic surfaces (in Cassie state) since they can trap air to prevent water droplets from filling the surface grooves.…”

A colloidal route to fabricate hierarchical sticky and non-sticky substrates

“…Moreover, it is well established that hierarchical roughness is important to ensure temporal stability of superhydrophobicity [26,27]. To construct superhydrophobic surfaces with hierarchical roughness, various methods and different techniques are used, such as LangmuirBlodgett deposition [28], nanosphere lithography [29], layerby-layer adsorption [30][31][32], binary colloidal assembly [33], sol-gel silica [34][35][36], polystyrene film preparation using electrohydrodynamics [37], carbon nanotube pattern generation [2,38,39], adsorption of charged submicrometer polystyrene latex particles [40], and laser etching of poly(dimethylsiloxane) (PDMS) surfaces [41].…”