Controlling self-patterning of acrylate films by photopolymerization†
Acrylate formulations can spontaneously generate surface patterns by UV-curing in open-air. This phenomenon, designated as self-patterning, occurs if there is a balance, at the film surface, between oxygen inhibition and polymerization rates. Indeed, to counterbalance the continuous oxygen diffusion at the film surface, polymerization kinetics has to be very fast. It can be achieved using acrylate monomers which are characterized by very high propagation rate constants. However, if the polymerization kinetics is too fast (for example using very high UV intensities) oxygen inhibition is strongly reduced at the surface, preventing self-patterning. Finally, highly ordered and long-range morphologies, such as hexagons, peanuts or lamellae, can be obtained. Their type and size can be tuned with easy-to-handle parameters such as the crosslinker concentration and the film thickness.