Molecular dynamics simulations of polyatomic-ion beam deposition-induced chemical modification of carbon nanotube/polymer composites

Considerable effort has been spent to incorporate carbon nanotubes into polymer matrices to exploit their extraordinary modulus and resistance to brittle failure. However, when as-synthesized nanotubes are used, the composites often fail through nanotube pullout due to poor adhesion between the nanotube and polymer matrix. Carbon nanotubes that are chemically functionalized, however, adhere more strongly to the polymer matrix because of efficient load-transfer through chemical bond formation between the polymer and the nanotube. In this work, the chemical modification of carbon nanotube/polystyrene composites via polyatomic ion beam deposition is investigated using molecular dynamics simulations. Several composite structures and incident ion energies are considered. The simulation results show that modification by ion beam deposition produces cross-links between otherwise unfunctionalized nanotubes and polymer backbone chains that serve to toughen the composite. High incident ion energies and compact composite structures are predicted to be optimum for effective chemical modification of the system.