Layered Montmorillonite/3D Carbon Nanotube Networks for Epoxy Composites with Enhanced Mechanical Strength and Thermal Properties

Because of their excellent thermal conductivities and high aspect ratios, carbon nanotubes (CNTs) exhibit great potential for use in microelectronic packaging. However, for their application in insulating materials, the high electroconductibility and poor radial conductivity of CNTs significantly limit their loading. In this work, a heterostructured "brushlike" hybrid was first prepared by anchoring aliphatic amine-functionalized multiwalled carbon nanotubes (MWCNTs) onto the insulating montmorillonite (Mt). The morphological characterizations of the heterostructured MWCNTs-Mt hybrids and epoxy composites were examined, revealing that a three-dimensional (3D) thermal conduction network within the matrix was constructed under the geometrical constraints of layered Mt. The synergistic effect of MWCNTs and Mt on the enhanced thermal conductivity and mechanical and thermal properties of the obtained composites was systematically established. The results showed that the thermal conductivity of MWCNTs-Mt/epoxy composites was significantly improved with the 0.5 wt % loading of hybrids, about 61% higher than that of pure epoxies; simultaneously, the dielectric loss of such composites was lower than that of pure epoxies at low frequencies, although the dielectric constant increased. Moreover, the mechanical properties and thermal stability of these composites were synchronously enhanced. This work provides a promising strategy for fabricating polymer composites with relatively high thermal conductivity, low dielectric loss, and excellent thermal stability and mechanical properties.