Nondestructive functionalization of carbon nanotubes by combining mussel-inspired chemistry and RAFT polymerization: Towards high dielectric nanocomposites with improved thermal management capability

Interface plays a critical role in determining the electrical properties and thermal management capability of carbon (e.g., nanotubes, graphene) based polymer nanocomposites. The strong interface is usually desirable and realized by forming the covalent interaction between nanocarbon and polymer matrix. However, the pristine properties, such as high electrical and thermal conductivity, of nanocarbon are inevitably deteriorated due to the introduction of lattice defects. In this work, a nondestructive strategy, combining mussel-inspired chemistry and surface initiated reversible addition fragmentation chain transfer (RAFT) polymerization, was developed to prepare lattice defect free interface between carbon nanotubes (CNTs) and epoxy resin. Polydopamine (PDA) was first coated on the CNT surfaces and then polymethyl methacrylate (PMMA) or polyglycidyl methacrylate (PGMA) macromolecular chains were grafted onto PDA encapsulated CNTs, which can result in non-covalent or covalent interface between CNTs and epoxy resin, respectively. It was found that PGMA encapsulated CNTs based epoxy nanocomposites show apparent advantages in increasing dielectric constants and suppressing dielectric loss tangent, as well as enhancing thermal conductivity. This study proves the superiority of the covalent interface formed by nondestructive functionalization in enhancing the dielectric properties and thermal management capability of nanocarbon based polymer composites.