Thermally Triggered Transition of Superhydrophobic Characteristics of Micro- and Nanotextured Multiscale Rough Surfaces

Abstract

In this paper, superhydrophobicity of multiscale hierarchical structures and wettability transition phenomenon of a water droplet on the superhydrophobic surface at different substrate temperature are extensively studied. Spin coating and spray coating methods have been regulated to fabricate EPF (Expanded polystyrene foam)/candle soot and EPF/camphor soot particle composites films. Maximum water contact angle of 165° and roll off angle of 2° were obtained with spray coated EPF/camphor soot composites which demonstrates their superhydrophobicity. By the measurement of water contact angle at different substrate temperature, we have demonstrated the influence of heat energy and pressure developed by micro water droplets during spreading phase. The reduction in water repellence observed on the protrusion induced hierarchical nanostructure is explained by the balancing pressure induced by a droplet of volume 4 µL and work of adhesion. The droplet contact area of hierarchical surfaces was profoundly influenced by change in viscosity of water droplets with temperature. The best performing spray coated EPF/camphor soot particle composite film impressively maintained superhydrophobicity with critical pressure of 200 Pa.The resulting insights can be used to tailor wettability of composite films, control liquid flow patterns for engineering applications such as micro-fluidics and bio-sensing devices.

Temperature Assisted in-Situ Small Angle X-ray Scattering Analysis of Ph-POSS/PC Polymer Nanocomposite

“…The hydrophobic characteristics of nanocomposite were outlined by measuring the contact angle of the sessile drop based on the apprehension developed by Balasubramanian et al . They have extensively explored the contact angle of various surfaces which predominantly depends on the surface roughness, surface energy and surface tension based on the proposed model of Cassie and Baxter 51 52 53 . In this context, we have contemplated hydrophobic attribute of developed polymer nano composite based on alteration in surface energy by the amalgamation of POSS units in PC matrix.…”

Superhydrophobic Civil Engineering Materials: A Review from Recent Developments

“…As can be seen in Figure 8a,b, they developed a superhydrophobic surface on paraffin ax-coated glass; it can be seen that the candle soot-coated slide demonstrated a large WCA of 162 • . Based on the development of the flame synthesis method, large numbers of researchers have tried to employ different approaches for stabilizing the flame-generated coatings, as at that time they possessed low mechanical durability [58][59][60][61][62][63][64][65][66]. Qahtan et al fabricated water jet-resistant and thermally stable superhydrophobic surfaces by a spray coating of candle soot dispersion [67].…”

Polycarbonate and activated charcoal-engineered electrospun nanofibers for selective recovery of oil/solvent from oily wastewater

“…The porosity generated in the PC nanofibers helps in the development of air-compartments i.e. pockets, between pores and heterogeneously patterned rough surface textures, thereby holding the water droplet on its surface, and maintaining the hydrophobicity [10,12,42,43]. This phenomenon is well elucidated by the Cassie-Baxter's theory, which interprets the hydrophobicity of heterogeneous rough patterned textures exhibiting porous nature.…”