Advanced morphological, statistical and molecular simulations analysis of laser-induced micro/nano multiscale surface relief gratings

A series of micro/nano structured azo-polyimide films via irradiation with a pulsed laser working at a wavelength of 355 nm, through a diffraction phase mask, using various incident fluencies and number of pulses was thoroughly investigated using Atomic Force Microscopy (AFM). The AFM analysis was preceded by a molecular modeling study. The influence of intrinsic factors materials on its micro/nano scale behavior, namely surface relief grating (SRG) induced by isomerization was investigated by all-atom molecular dynamics simulations. For this purpose, the free volume and mean square displacement were measured. The effect of the azochromophore type (azobenzene or azopyridine), the chemical structure of the polymer backbone, and the irradiation conditions on the morphological aspect of the SRGs were investigated. The competing mechanisms that lead to the formation of progressively distinguished compact linear periodic three-dimensional grooves with ridges relatively flatten, exhibiting no supplementary organization at a low number of pulses or to hierarchical micro/nano multiscale surface relief gratings at a high number of pulses were explained. The interdependence of the statistical texture parameters with the irradiation conditions and chemical structure of the azo-polyimide is important in controlling the contact area of the patterned azo-polyimide surfaces at the interface with other materials for optoelectronic devices.