Researchers have discovered a way to create materials that are both stiff and capable of insulating against heat.
This unique combination of properties could lead to new thermal insulation coatings for electronic devices, among other applications.
Typically, materials that are stiff (high elastic modulus) are also good at conducting heat, while materials that are not stiff are better at insulating against heat.
This makes it challenging to find materials that are both stiff and good insulators.
Jun Liu, an associate professor of mechanical and aerospace engineering at North Carolina State University, explains, “There are instances where you’d want materials that are stiff but also good insulators, such as in thermal insulation coatings to protect electronics from high temperatures. Historically, this has been difficult to achieve.”
However, Liu and his colleagues have discovered a range of materials that meet both criteria. They focused on a subset of two-dimensional hybrid organic-inorganic perovskites (2D HOIP).
Their findings are detailed in the paper, “Anomalous correlation between thermal conductivity and elastic modulus in two-dimensional hybrid metal halide perovskites,” published in ACS Nano.
Wei You, a professor at the University of North Carolina at Chapel Hill, explains, “These are thin films made of alternating organic and inorganic layers in a highly ordered crystalline structure. We can adjust the composition of either layer.”
Qing Tu, an assistant professor at Texas A&M University, adds, “By replacing some of the carbon-carbon chains in the organic layers with benzene rings, we found we could control both the stiffness and thermal conductivity of the materials. More benzene rings made the material stiffer and better at insulating against heat.”
The team identified at least three distinct 2D HOIP materials that became less thermally conductive as they got stiffer. This discovery is significant because it suggests a new way to engineer materials with desirable properties.
Liu highlights the importance of their findings, “We’ve identified the critical role that benzene rings play in these materials. Understanding this mechanism opens up new possibilities for designing materials with specific characteristics.”
Another fascinating discovery involves the introduction of chirality into the organic layers. By making the carbon chains asymmetrical, researchers found they could maintain the same stiffness and thermal conductivity even when making significant changes to the composition of the organic layers.
“This raises interesting questions about whether we might be able to optimize other characteristics of these materials without affecting their stiffness or thermal conductivity,” says Liu.
In summary, the researchers have developed materials that combine stiffness and heat resistance, a rare and valuable combination. This breakthrough could lead to new applications in electronic device protection and other fields, demonstrating a promising new pathway for material engineering.
