Non-Wettable Surfaces – From Natural to Artificial and Applications: A Critical Review

Abstract

Non-wettable surfaces have recently attracted significant attention due to their enormous promising applications. These applications are primarily due to their ability to repel liquid drops and remain unwetted. In this review, the various names used in describing non-wettable surfaces are given. This is followed by the fundamental theories of wetting. Natural non-wettable surfaces are then considered, along with their importance. Thereafter, we discuss how artificial non-wettable (biomimetic) surfaces are prepared. Next, the basic properties of non-wettable surfaces, which make them promising candidates for a wide range of applications, are discussed. Furthermore, the various applications of non-wettable surfaces are discussed, with references made to review articles with specific coverage of named applications. We conclude with a summary, challenges limiting the application of non-wettable surfaces to some real-life situations and possible suggestions to mitigate them as well as opportunities for future work.

Antibacterial Properties of Triethoxysilylpropyl Succinic Anhydride Silane (TESPSA) on Titanium Dental Implants

“…As previously commented, cell and bacterial adhesion is also related with the wettability and surface free energy (SFE) due to surface exposed hydrophobic or hydrophilic chemical groups [49][50][51]. As shown in Table 2, contact angle values of Ti-N-TSP decreased compared to Ti.…”

Influence of particle fluorination on the stability of honey foam

“…Placing powdered particles on a liquid surface and observing whether or not they sink into the liquid provides a qualitative measure of the extent to which the particles are wetted by the liquid. Upon aerating such a particle-liquid mixture, the particles become suspended in the liquid if they are completely wetted by the liquid (i.e., sank into it), but they coat surfaces of air bubbles and produce foam if they are partially wetted by the liquid (i.e., does not sink into it) (Tyowua et al, 2019). Both the hydrocarbon-and fluorocarbon-coated particles were partially wetted by the honey sample, thus aerating the particle-honey mixture yielded honey foam.…”

“…When the contact angle is greater than 90 °, the particles are hydrophobic (water) and oleophobic (oil) (Tyowua et al, 2019). We extend this nomenclature to describe these particles (contact angle >90 °) in terms of honey as "honephobic."…”

“…We extend this nomenclature to describe these particles (contact angle >90 °) in terms of honey as "honephobic." The corresponding description for contact angle <90 °is hydrophilic (water) and oleophilic (oil) (Tyowua et al, 2019), which can be extended to honey as "honephilic." This nomenclature is necessary because although honey is a concentrated aqueous solution of sugars (mainly fructose and sucrose), it has a relatively higher surface tension (80.4 mN m −1 , 30 °C) compared with the surface tension of water (71.2 mN m −1 , 30 °C, Haynes et al, 2016), meaning it will wet surfaces or particles differently from water.…”