Design and Application of Surfaces with Tunable Adhesion to Liquids and Solids
Fouling affects a wide range of industries around the globe. The two main categories of fouling are the unwanted adhesion of solids, and the unwanted adsorption of liquids. The purpose of this thesis is to understand and design new mechanisms to mitigate fouling. As fouling always occurs at the interface between a surface and the foulant, the main strategy employed in this work is the fabrication of designer coatings that can be applied to any surface, such that the foulant is repelled.
In the first half of this dissertation I discuss new methods for reducing the adhesion of ice to surfaces. Ice adhesion routinely hinders many industries world-wide, and to-date there have been few long-term strategies to mitigate ice adhesion. We first design elastomeric coatings exhibiting the lowest ice adhesion strengths ever reported, and formulate a predictive model for the phenomenon of interfacial slippage, such that the ice adhesion strength of any surface can be rationally designed. We then utilize fracture mechanics to design surfaces exhibiting low interfacial toughness with ice, such that the force to remove the accreted ice becomes independent of the iced area. These results contradict the last 70 years of ice-adhesion analysis.
One of our new techniques for repelling ice, and solid foulants in general, is the fabrication of liquid-like, covalently grafted monolayers. We show that surfaces treated with these monolayers also exhibit extreme liquid repellency, including the first-ever reported fluorophobic surfaces (i.e. surfaces that repel extremely low surface tension, fluorinated liquids). The second half of this thesis discusses various new ways of repelling a wide variety of different fouling liquids. We fabricate optically transparent surfaces capable of repelling a wide variety of low surface tension liquids. We also design extremely mechanically robust superhydrophobic surfaces that can self- heal after physical and chemical damage. Finally, we utilize some of these water- repellent systems to effectively reduce friction drag in turbulent flow.
Chair: Assoc. Prof. Anish Tuteja, MSE
Prof. Jinsang Kim, MSE Prof. Michael Thouless, ME, MSE
Assoc. Prof. Pramod Reddy, ME, MSE