Session: Government Agency Student Posters

Paper Number: 173304

Strain Effect on Thermal Transport in 3d Nanostructures 

This study investigates how mechanical strain influences thermal transport in three-dimensional (3D) nanostructures, focusing on pillared graphene and pillared hexagonal boron nitride nanosheet (hBNNS) systems. Molecular dynamics simulations were employed using reverse nonequilibrium molecular dynamics (RNEMD) and phonon wavepacket analysis, in combination with the AIREBO, PCFF, and Tersoff force fields.

Understanding interfacial thermal resistance in such 3D nanostructures is essential for the development of advanced nanomaterials, particularly in applications such as next-generation energy storage systems and flexible electronics. These applications increasingly demand materials that can manage heat efficiently while maintaining electrical insulation and mechanical flexibility. As such, graphene and hBN-based 3D nanostructures are at the forefront of thermal interface design.

For both carbon-based and hBN-based 3D architectures, our simulations show that interfacial thermal resistance at the junction is substantially lower than that typically found in conventional materials such as polymers or metal interfaces. This low resistance indicates highly efficient heat transfer at the nanoscale, primarily driven by effective phonon coupling across the interface. These findings point to the potential of 3D nanostructures as high-performance alternatives to traditional thermal interface materials—particularly in miniaturized systems where both compactness and thermal management are critical.

In hBN-based 3D nanostructures, increasing the height of the nanotube pillars consistently reduces interfacial thermal resistance. This trend suggests that longer nanotubes facilitate the transmission of low-frequency, long-wavelength phonons, which can travel farther with fewer scattering events. These results imply that thermal transport in pillared hBNNS structures remains largely ballistic and that phonon mode conversion across the junctions is highly efficient. However, when tensile strain is applied vertically, the interfacial thermal resistance increases. This rise is attributed to the elongation of interatomic bonds at the junctions, which disrupts phonon transport pathways by altering local vibrational modes and reducing phonon transmission efficiency.

While the directionality of phonon transport becomes less pronounced under strain, the overall impact of lattice distortion on phonon mode conversion is detrimental. Strain-induced distortions introduce additional phonon scattering centers and break structural symmetry, thereby reducing the overall thermal conductivity.

In contrast, carbon-based 3D nanostructures exhibit a different behavior. Here, tensile strain leads to a steady increase in thermal conductivity. For example, a 0.1 tensile strain results in a 22.4% enhancement in thermal conductivity. This improvement is more pronounced with longer graphene spans between pillars, which accommodate greater deformations without bond failure. Phonon wavepacket analysis confirms that tensile deformation enhances the transmission of low-frequency longitudinal and transverse acoustic phonons—key energy carriers in these systems. In contrast, twisting and flexural phonon modes are largely unaffected by strain. Moreover, phonons with higher group velocities were found to transmit more effectively, further supporting the correlation between group velocity and interfacial transmission efficiency.

Overall, these results demonstrate that structural geometry and strain can be strategically leveraged to modulate thermal transport in 3D nanostructures, offering pathways for engineering flexible, high-performance thermal interface materials.

Presenting Author: Josh Ellison Kennesaw State University

Presenting Author Biography: Josh Ellison is an undergraduate student researcher at Kennesaw State University

Authors:

Josh Ellison Kennesaw State University
Jungkyu Park Kennesaw State University