Interfacial thermal conduction mechanism of polypyrrole/carbon nanotube composites

The excellent properties of carbon nanotube (CNT) make it possible for CNT-based materials to have both high thermal conductivity and high electrical conductivity. However, the weak coupling between the CNTs results in these properties far below expectations, which seriously hinders the application of CNT-based materials. The approaches to improve the electrical conductivity or the thermal conductivity are usually considered separately, but the heat generated by low resistance at high frequencies cannot be ignored and both of them need be focused. Loading polypyrrole (PPy) into the grooves between CNTs is a common method to improve electrical conductivity of CNT-based materials, which may also increase thermal conductivity through its polymer characters. This work finds that PPy fills the space of the grooves between CNTs, acts as the role of thermal transport relay, and builds a more stable heat transfer channel. And the PPy also resonates with carbon atoms, results in the phonon mode variation and interfacial phonon mismatch level change. The interfacial thermal conduction of CNTs significantly improves up to 202 %. This provides new design ideas for advanced CNT-based electronic devices.