We report a new surface-initiated polymerization strategy that yields superhydrophobic polymethylene (PM) films from initially smooth substrates of gold and silicon. The films are prepared by assembling a vinyl-terminated self-assembled monolayer, followed by exposure of the surface to a 0.1 M solution of borane, and polymerizing from the borane sites upon exposure to a solution of diazomethane...

Regular arrays of micro-pillars and nano-grooves structures on the silicon wafer are fabricated by using soft lithography, and the three dimension morphology of textured surface is observed by using scanning electron microscopy (SEM) and atomic force microscope (AFM). The static water contact angles are measured by using contact angle meter to characterize the wettabilities of these surfaces. T...

A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA) within a low-shrinkage acrylated hyperbranched polymer (HBP) and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the ...

Electrowetting devices with an initial superhydrophobic water contact angle (>150◦) have now been demonstrated on a variety of structured substrates. These substrates are more complex than a conventional superhydrophobic surface since electrowetting requires an electrical conductor that is coated with a highperformance dielectric and a hydrophobic fluoropolymer. Substrate structures that have b...

Thin organic films containing carbon nanotubes (CNTs) have received increasing attention in many fields. In this study, a robust thin superhydrophobic film has been created by using layer-by-layer assembly of the carbon nanotubes wrapped by poly(dopamine) (CNT@PDA) and poly(ethyleneimine) (PEI). UV-vis spectroscopy, ellipsometry, and quartz crystal microbalance with dissipation (QCM-D) measurem...

Dropwise condensation processes, where condensation occurs through small droplets on a solid surface, has been demonstrated to significantly improve heat transfer rates in comparison to film-wise condensation (where a whole surface is covered by a thin film of liquid). Dropwise condensation usually takes place on superhydrophobic surfaces, and one of the main engineering and scientific challeng...

Inspired by some typical plants such as lotus leaves, superhydrophobic surfaces are commonly prepared by a combination of low surface energy materials and hierarchical micro/nano structures. In this work, superhydrophobic surfaces on copper substrates were prepared by a rapid, facile one-step pulse electrodepositing process, with different duty ratios in an electrolyte containing lanthanum chlo...

Superhydrophobic surfaces in nature exhibit desirable properties including self-cleaning, bacterial resistance, and flight efficiency. However, creating such intricate multi-scale features with conventional fabrication approaches is difficult, expensive, and not scalable. By patterning photoresist on pre-stressed shrink-wrap film, which contracts by 95% in surface area when heated, such feature...

Dash, Susmita. Ph.D., Purdue University, December 2014. Droplet Behavior on Superhydrophobic Surfaces: Interfaces, Interactions, and Transport. Major Professor: Suresh V. Garimella, School of Mechanical Engineering. The primary objective of the present work is to study droplet dynamics on smooth hydrophobic and textured superhydrophobic surfaces, and to understand the dependence of interfacial ...

Evaporation rates are predicted and important transport mechanisms identified for evaporation of water droplets on hydrophobic (contact angle ~110°) and superhydrophobic (contact angle ~160°) substrates. Analytical models for droplet evaporation in the literature are usually simplified to include only vapor diffusion in the gas domain, and the system is assumed to be isothermal. In the comprehe...