Transparent Superhydrophobic Films Based on Silica Nanoparticles

Abstract

We demonstrate a layer-by-layer processing scheme that can be utilized to create transparent superhydrophobic films from SiO2 nanoparticles of various sizes. By controlling the placement and level of aggregation of differently sized nanoparticles within the resultant multilayer thin film, it is possible to optimize the level of surface roughness to achieve superhydrophobic behavior with limited light scattering. Transparent superhydrophobic films were created by the sequential adsorption of silica nanoparticles and poly(allylamine hydrochloride). The final assembly was rendered superhydrophobic with silane treatment. Optical transmission levels above 90% throughout most of the visible region of the spectrum were realized in optimized coatings. Advancing water droplet contact angles as high as 160 degrees with low contact angle hysteresis (<10 degrees ) were obtained for the optimized multilayer thin films. Because of the low refractive index of the resultant porous multilayer films, they also exhibited antireflection properties.

A colloidoscope of colloid-based porous materials and their uses

“…Polydisperse particles, which are unable to crystallize in an ordered matrix, can be used to prepare amorphous assemblies without long-range order ( Figure 3B). 4,82 Simplistic and scalable approaches such as spray coating 83,84 or layer-by-layer assembly 85,86 of particles that are not suitable for crystallization due to high attractive forces or insufficient crystallization time can still be used to prepare disordered assembly structures in an experimentally straightforward way. Indeed, as we discuss in detail in several of the following sections, order is not necessary for every application of CBPM, and controlled disorder may even create desired properties.…”

“…[189][190][191][192][193] Colloids can also be used for antireflective coating applications. 85 In particular, colloidal monolayers have been used to create porous, graded-index materials with low reflectivity by, for example, plasma etching of colloidal monolayers, 194 inverting the monolayer, 95 or using the monolayer as an etching mask to generate pillars. 166,187,195 To reduce the reflection from the top surface of solar cells, many methods are used to generate porous materials with the proper optical thickness and effective index for optimal transmission.…”

Polymeric optical fibre sensor coated by SiO2 nanoparticles for humidity sensing in the skin microenvironment

“…In this case, the POFHS has a refractive index of 1.49 and 1.22 for the core and the hydrophilic film [25], respectively. For measurements at the wavelength peak of 611nm and angle of incidence 57°, the penetration depth of the EW is approximately 360nm.…”

Studies on the thermal properties and flammability of polyamide 6 nanocomposites surface-modified via layer-by-layer deposition of chitosan and montmorillonite

“…Since then, many practical applications of this surface treatment method have been described, such as in electrochromic materials [3][4][5], controlled drug delivery [6,7], composites with barrier properties towards oxygen [8][9][10][11][12], antireflective [13] and waterproof coatings [14][15][16], and antibacterial materials [17][18][19]. In principle, LbL assemblies arise from alternative dipping of substrates in, most often, water-based solutions of polyelectrolytes, which makes this method eco-friendly.…”