Nanoporous structures of polyimide induced by Ar ion beam irradiation

The surface morphology evolution of polyimide (PI) that was treated with an Ar ion beam was explored using a hybrid ion beam system. A hole-like nanostructure formed on PI during the Ar ion beam treatment at a lower fluence, but PI formed 3D porous nanostructures with a mean diameter of ∼90 nm at a higher fluence. The chemical binding energy and the composition of the Ar ion irradiated PI were analyzed using FT-IR and XPS spectra, which revealed that the polymer chain scissioning increased with increasing Ar ion treatment duration, i.e., fluence. The surface hardness and the elastic modulus of PI increased from 1.17 to 1.62 GPa and 4.06 to 5.41 GPa, respectively, with respect to the Ar ion beam treatment duration.