Exploring the interface between single-walled carbon nanotubes and epoxy resin

A significant mechanical reinforcement of epoxy matrices with carbon nanotubes (CNTs) requires a very strong covalent interfacial bonding between the tube and the resin, diglycidylether of bisphenol A (DGEBA). Using classical molecular dynamics (MD) and density functional theory (DFT), various methods of improving covalent binding to CNTs are applied on four major categories: CNT diameters, dopants, defects, and functional groups. The diameter category includes (n, 0) CNTs with n = 5, 7, 9,11, 13, 15; the dopant category includes B-, N-, and Si-doped CNTs; the defect category includes CNTs with monovacancies, Stone-Wales, and more complex nitrogen terminated monovacancies and divacancies; the functional group category includes CNTs with atomic oxygen, hydroxyl, amine, carboxyl, and a combination of oxygen and hydroxyl. The computation of binding energies (BE), affinity indices (AI), and shear fracture forces on all configurations converged to the conclusion that smaller tubes, Si-doped CNTs, CNTs functionalized with a combination of oxygen and hydroxyl, and CNTs with monovacancies show the strongest indication for mechanical reinforcement in their respective categories.