Tailoring the adhesion properties of thin polymeric films using additives: an AFM study

This study investigates the modification of adhesive properties in UV-cured thin films, commonly used in many fields ranging from protective coatings to primer layers for printing. We incorporated two types of additives into a 12 µm thick polymer film: one additive containing silicone-modified polyethers and another additive containing silicone-free modified polyethers. Our findings indicate that both additives segregate towards the film's surface, altering the surface properties without affecting the bulk. Using atomic force microscopy, we measured the adhesive work from force-distance curves, observing improved adhesive properties up to an optimal concentration of 10 wt%. Beyond this concentration, the film's adhesion plateau, with excess additives assimilating into the film's bulk which we interpret as being consistent with a change in the near-surface polymer ordering. Concentration-dependent measurements suggest a change in nanomechanical response above 10 wt%. This indicates that the films above this concentration undergo a drastic change, which we attribute to either capillary interaction, molecular ordering or additional crosslinking between the additive and base polymer mixture. Our results provide a deeper understanding of polymeric surface modification, which is paramount for flexographic printing of metallic surfaces using 2D flakes and thin polymer films.