Invited Conference: Photoinduced processes for polymer patterning and surface modification
Alessandra Vitale, assistant professor at the Polytechnic Institute of Turin, invited researcher at MAPIEM, will give a conference on Thursday, February 22nd, at 1:00 p.m. entitled "Photoinduced processes for patterning polymer and area change."
Her research work is particularly focused on photopolymerization techniques in order to structure or texture polymers at nanometric and micrometric scales.
UV curing of photopolymerizable formulations has been used for more than a half century for protective and decorative coatings of paper, wood, metals or plastics. Advantages can for sure been found in the high curing speed that allows the conversion of typically (meth)acrylate-based monomers within the fraction of a second. We demonstrate that photopolymerization processes can also be used to finely control and localize the surface chemistry, architecture and properties (e.g., wettability, bioadhesion, mechanical and swelling properties) of crosslinked materials.
For instance, the inhibitory effects of oxygen during UV curing in air can be exploited to fabricate multiscale and multimaterial patterns and devices. By tuning the curing kinetics and parameters, both surface topography and functionality are controlled with high fidelity over a variety of feature sizes and heights, and multifunctional structures of varied and complex shapes, containing different compositions and thus showing a synergy of properties, are fabricated.
Moreover, photopolymerization can also be used for generating gradient polymers in a single step and for independently and simultaneously controlling their surface and bulk properties. Thanks to the introduction of a small amount (≤1 wt.%) of a low polarity comonomer (i.e., siloxane or perfluoropolyether) and its spontaneous migration towards the free surface, and by controlling the photopolymerization conditions, such as the light gradient through the thickness of the film, it is possible to optimize and photoenforce the surface segregation of the apolar comonomer, producing films characterized by a low surface energy.