Design and fabrication of highly hydrophobic Mn nano-sculptured thin films and evaluation of surface properties on hydrophobicity

Abstract

The wettability of solid surfaces is important from the aspects of both science and technology. The Mn nano-sculptured thin films were designed and fabricated by oblique angle deposition of Mn on glass substrates at room temperature. The obtained structure was characterized by field emission scanning electron microscopy and atomic force microscopy. The wettability of thin films samples was investigated by water contact angle (WCA). The 4-pointed helical star-shaped structure exhibits hydrophobicity with static WCAs of more than 133°for a 10-mg distilled water droplet. This sample also shows the rose petal effect with the additional property of high adhesion. The Mn nano-sculptured thin films also act as a sticky surface which is confirmed by hysteresis of the contact angle obtained from advancing and receding contact angles measurements. Physicochemical property of liquid phase could effectively change the contact angle, and polar solvents in contact with hydrophobic solid surfaces do not necessarily show high contact angle value.

Tuning the wettability of metal surface with electrodeposited porous copper and graphene coatings

“…It occurs in the case of an external force, such as pressure or vibration applied to the liquid. It is reported that increasing Laplace pressure induced this transition [63]. Additionally, altering of surface roughness or increasing such as structure's holes depth, making the shift from Cassie-Baster state to Wenzel state easier [167,168].…”

“…The wettability of surfaces can be evaluated by measuring the contact angle (CA) of a liquid on a surface and its surface tension, which is described by Young's equation. Between the solid/liquid interface, the droplet can be flattened or rolled off according to the degree of contact angle value (from 0° to 180°) [60][61][62][63].…”

“…In 1936, Wenzel described the effect of surface roughness r on the wettability of a homogenous surface and proposed an equation based on the complete wetting of a rough surface. According to the Wenzel model as a classical situation of a droplet on a flat surface, the liquid penetrates between the grooves of a structure, and it is not valid for a heterogeneous surface Figure 14 [63,160]. Wenzel modified Young's equation, which demonstrates the relationship between three factors: equilibrium contact angle (Young angle θY), roughness factor and apparent contact angle [161].…”