Magnetic-field-induced alignment of metal nanoparticles in polymer - Experiments and molecular dynamics simulation

A one-dimensional ordered nanocomposite was fabricated by utilizing magnetic field to control the alignment of carbon-coated nickel(Ni@C) nanoparticles in epoxy resin. It exhibits an excellent improvement in electrical conductance and dielectric constant. With the loading mass fraction of 3%-10%, the resistivity of resulting composite decreases by 3 orders of magnitude with respect to unaligned composite. A molecular dynamics model was designed to simulate the structure evolution of nanoparticles in resin curing. The simulated results show that the alignment of nanoparticles arises from the dominant magnetic dipolar interaction, and experiences a shift from aggregation to chaining then to chain thickening; the time scale for chain growth is the order of seconds, there is nearly not dynamics barrier for the alignment of Ni@C nanoparticles in epoxy resin; the simulated structure agrees basically with those observed in experiments.