Ambipolar Charging Responses of Nanoscale Interfaces

Low-dimensional <i>sp</i>²-based carbon nanostructures, known for their remarkable transport properties and mechanical behaviors, are widely used as reinforcing phases in polymer composites to enhance their performance. While carbon nanocomposites are promising materials for extreme conditions, the damage mechanisms due to charge injection at the interfaces between carbon nanostructures and polymers remain unclear. Using first-principles calculations, we investigated ambipolar charging and structural responses at the interfaces between industrially relevant polymers and carbon nanotubes or graphene upon electron and hole injection. Our electronic structure analysis reveals that resistance to charge injection is closely related to the band structures of the polymers and the chemistry of interfacial cross-links. Mechanical behaviors assessed through traction and shear tests reflect changes in electronic coupling at the interfaces. Our results indicate significantly degraded mechanical performance with electron injection, while slight hole injection leads to shortening and stiffening of covalent bonds. These findings provide crucial insights for the design of carbon nanocomposites intended for harsh environments, such as lightning strikes and high-power electromagnetic shocks.