ERI: Fundamental Insights into Self-Repairing Mechanisms in Superhydrophobic Coatings

About This Grant

Superhydrophobic coatings, which cause high surface tension liquids such as water to bead up and roll off have extensive applications in drag reduction, corrosion protection, self-cleaning materials, ice resistance, and liquid separation. However their commercial use has been limited due to poor durability under mechanical abrasion. Even a minor damage to the surface texture can compromise their liquid-repellent properties. This Engineering Research Initiative (ERI) project aims to support research that address this long-standing limitation by advancing sustainable, vegetable oil-based superhydrophobic polymer coatings that can self-repair even significant damage, including deep scratches, through a unique viscous flow mechanism that can recover original coating’s function. Through systematic experimentation and computational modeling, this research looks to uncover the relationships between key material properties and parameters that govern the viscous flow-driven mechanism. Advancing the science of self-repairing coatings in this project seeks to contribute to broader societal impacts including extending the lifespan of infrastructure, decreasing maintenance costs, and conserving national resources. The efforts in this project will be complemented by mentorship and training of undergraduate and graduate students by direct research involvement, integrating insights from this research into a materials science course to improve undergraduate education, developing a graduate-level course module on surface science and engineering, engaging in public outreach and STEM activities (such as coatings preparation training sessions during summer camps), and inspiring students to pursue practical STEM-related fields. The project goal is to experimentally and mathematically investigate how key material parameters, including viscosity and interfacial tension, affect the kinetics and extent of viscous flow-driven damage recovery in self-repairing superhydrophobic coatings. Vegetable oil-based polymer coatings will be synthesized with systematically varied molar mass, crosslinking density, and hydrophobic modifiers to control these key parameters. Surface texture will be introduced using nanoparticles and the multiscale effects on superhydrophobic wettability will be investigated. Viscosity measurements along with interfacial tension estimations, will be correlated with self-repairing performance through controlled scratch-repairing experiments. A model based on film relaxation and leveling will describe the time-dependent repairing behavior and predict self-repairing efficiency as a function of material properties and damage geometry. Application validation will be performed by assessing the reductions in water-induced frictional resistance before and after self-repairing of damage. These efforts aim to advance the fundamental understanding of the self-repairing process and establish design frameworks for durable self-repairing superhydrophobic surfaces and coatings tailored to specific damage conditions and application requirements. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.