Temperature Dependence of Surface Energy of Ice and its Implications on Adhesion and Friction

University Of Akron, Akron OH

Investigators

Abstract

With support from the Chemical Structure, Dynamics and Mechanisms-A Program (CSDM-A) program in the Division of Chemistry, Professor Ali Dhinojwala of The University of Akron is investigating the temperature dependence of the surface energy of ice and how it influences adhesion and friction. As the surfaces of ice are covered with a water-like surface layer, this is expected to impact the surface energy, adhesion, and friction. Professor Dhinojwala and his students are using advanced spectroscopy techniques to study the contact interface between ice and a soft elastomer and how the structure of this interface changes with temperature. Their work will shed light on the transition temperature of the liquid-like layer of water and its influence on the surface energy of ice. Their discoveries could lead to the design of new materials or coatings for higher traction on ice such as winter tires and shoe soles; for ice-resistant surfaces and anti-icing coatings on aircraft, high voltage cables, and wind turbine blades; and materials to improve food preservation. Dr. Dhinojwala is promoting STEM (science, technology, engineering and mathematics)-related outreach activities as a Director of District Science Day and the co-director of the Biomimicry Center, and he is designing an honors class on materials that have influenced human civilization. This project seeks to reveal the molecular level details of an observation made by Professor Dhinojwala and his students, namely an abrupt transition in adhesion energy between a siloxane elastomer and an ice surface at 257 K (16 K below the bulk melting temperature of ice). Dhinojwala and his team hypoethesize that this change in adhesion energy is due to an abrupt transition of the bilayer of ice and potentially a change in the surface energy of the ice. Because both adhesion and friction will also be influenced by this transition, Dhinojwala’s research team is using the Johnson–Kendall–Roberts geometry to measure the thermodynamic work of adhesion and compare it to the temperature dependence of surface energy. The team is using a new interface-sensitive sum frequency generation spectroscopy (SFG) technique to study the contact interface between ice and soft elastomers, a problem of fundamental importance in understanding adhesion and friction of ice surfaces. Dhinojwala’s team is applying these measurements to study the influence of roughness and correlate with Persson’s predictions on how ice adhesion and friction are affected by roughness. The broader impacts of this research in technological applications stem from new insights that relate interfacial molecular structure to macroscopic friction coefficients. 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.