Paraffin confined in carbon nanotubes as nano-encapsulated phase change materials: experimental and molecular dynamics studies

Abstract

The characteristics of paraffin confined in carbon nanotubes (CNTs) were investigated using experimental and molecular dynamics (MD) methods. Through a vacuum infiltration process, paraffin was successfully infiltrated into the inner space of CNTs, which was proven by TEM and DSC observations. The melting point and latent heat were both lower than the bulk. Furthermore, MD simulations were performed to provide insight into the structural distribution of paraffin confined in CNTs and to attempt to find an explanation of the experimental results. The MD simulation results indicated that paraffin molecules exhibited an orderly structural distribution near the inner wall of the CNTs, which gradually turned disorderly with increasing temperature. The self-diffusion coefficient compared with that of pure paraffin increased. These behaviors could be attributed to the nano-confined environment of the CNTs and the interaction between the paraffin molecules and the tube walls. The current research is significant for understanding the behaviors of alkane-based phase change materials inside CNTs, which could provide new applications of paraffin in microelectronics cooling.