A Lipid-Inspired Highly Adhesive Interface for Durable Superhydrophobicity in Wet Environments and Stable Jumping Droplet Condensation

Abstract

Creating thin (<100 nm) hydrophobic coatings that are durable in wet conditions remains challenging. Although the dropwise condensation of steam on thin hydrophobic coatings can enhance condensation heat transfer by 1000%, these coatings easily delaminate. Designing interfaces with high adhesion while maintaining a nanoscale coating thickness is key to overcoming this challenge. In nature, cell membranes face this same challenge where nanometer-thick lipid bilayers achieve high adhesion in wet environments to maintain integrity. Nature ensures this adhesion by forming a lipid interface having two nonpolar surfaces, demonstrating high physicochemical resistance to biofluids attempting to open the interface. Here, developing an artificial lipid-like interface that utilizes fluorine−carbon molecular chains can achieve durable nanometric hydrophobic coatings. The application of our approach to create a superhydrophobic material shows high stability during jumping-droplet-enhanced condensation as quantified from a continual one-year steam condensation experiment. The jumping-droplet condensation enhanced condensation heat transfer coefficient up to 400% on tube samples when compared to filmwise condensation on bare copper. Our bioinspired materials design principle can be followed to develop many durable hydrophobic surfaces using alternate substrate-coating pairs, providing stable hydrophobicity or superhydrophobicity to a plethora of applications.

Polydimethylsiloxane‐Silane Synergy enables Dropwise Condensation of Low Surface Tension Liquids

“…Furthermore, the PDMS coated surface suffers from the formation of filmwise condensation of low surface tension liquids due to condensate penetration through the coating layer as illustrated in Figure 2F‐I. However, coupling of the flexible siloxane polymer with the low energy silane prevents filmwise condensation due enhancement of the coating wet adhesion, [ 38 ] and prevention of condensate penetration by the dense fluoroalkyl silane layer tethered to the PDMS on the siloxane‐silane coated substrate as depicted in Figure 2F‐II. As a result of the multi‐layer impenetrable structure, the dual layer siloxane‐silane coating is durable and enables long term sustainable dropwise condensation of low surface tension liquids.…”

Enabling Renewable Energy Technologies in Harsh Climates with Ultra‐Efficient Electro‐Thermal Desnowing, Defrosting, and Deicing

“…[ 54 ] Recently developed durable superhydrophobic coating designs having >1 year prolonged durability in wet conditions can be adopted to our technology to enhance robustness. [ 55 ]…”

“…[54] Recently developed durable superhydrophobic coating designs having >1 year prolonged durability in wet conditions can be adopted to our technology to enhance robustness. [55] Large scale (>1 m 2 ) sputtering of thin films on various substrates (metals, glass, and polymers) and various substrate geometries (flat, convex, and concave) is established and used in multiple industries. [56] The total cost of the large-scale deposition systems needs to be considered while conducting techno-economic analysis of our technology.…”

Ultrascalable Surface Structuring Strategy of Metal Additively Manufactured Materials for Enhanced Condensation

“…Improvements in durability of low surface energy nanoscale promoter coatings, on the other hand, can be realized by increasing the coating interfacial adhesion to prevent delamination in wet environments. Recent work has demonstrated that the utilization of lipid‐like bilayer coatings have the potential to exhibit such durability, hence, prolonging jumping‐droplet condensation for more than 8000 h. [ 74 ] Therefore, combining our AM nanostructuring strategy with lipid‐like bilayer coatings presents a feasible approach towards realizing jumping‐droplet enhanced condensation for industrial scale application and can be investigated in the future.…”