Analysis of photopolymerized acrylic films by AFM in pulsed force mode.

This paper highlights the potential of atomic force microscopy in the pulsed force mode to investigate the photopatterning of acrylic-based films. The pulsed force mode is a nonresonant mode designed to allow approach curves to be recorded along the scanning path. It thereby provides the topography of the sample and a direct and simple local characterization of adhesion and stiffness. This mode can be used either for imaging or for locally probing the mechanical properties of a surface. In particular, a correlation between stiffness and conversion of the monomer was established. The close examination of the pulsed force mode signal brought accurate information on the photoinduced modification of the film. Polymer films with submicron photopatterning generated by interferometric illumination were analyzed by pulsed force mode. It was established that the gradient of mechanical properties throughout the films was strongly dependant on the irradiation conditions.