Materials Science and Engineering

Researchers have discovered a strong correlation between the speed at which heat moves between two touching materials and how strongly those materials are bonded together.

The speed at which heat moves between two materials touching each other is a potent indicator of how strongly they are bonded to each other, according to a new study by researchers at Rensselaer.

Additionally, the study shows that this flow of heat from one material to another can be dramatically altered by “painting” a thin atomic layer between materials. Changing the interface fundamentally changes the way the materials interact.

“If you have a nanoparticle that is inside a liquid solution, you can’t just ‘peel away’ the liquid to measure how strongly it is bonded to the surrounding molecules,” says Pawel Keblinski, professor of materials science and engineering, who co-led the study. “Instead, we show that you can measure the strength of these bonds simply by measuring the rate of heat flow from the nanoparticle to the surrounding liquid.”

“Interfaces are an exciting new frontier for doing fundamental studies of this type. If you peek into complex biological systems—a cell, for example—they contain a high density of interfaces, between different proteins or between protein and water,” says Shekhar Garde, the Elaine and Jack S. Parker Professor and head of the Department of Chemical and Biological Engineering, who co-led the study. “Our approach possibly provides another handle to quantify how proteins talk to each other or with the surrounding water.”

Keblinski and Garde used extensive molecular dynamics simulations to measure the heat flow between a variety of solid surfaces and water. They simulated a broad range of surface chemistries and showed that thermal conductance, or how fast heat is transferred between a liquid and a solid, is directly proportional to how strongly the liquid adhered to the solid.

“In the case of a mercury thermometer, thermal expansion correlates directly with temperature,” Keblinski says. “What we have done, in a sense, is create a new thermometer to measure the interfacial bonding properties between liquids and solids.”