Digital Printing of Photoreversible Protective Films

Abstract

Temporary protective coatings are widely used in modern production processes. Yet, while highly desirable, their high-resolution printing and stimuli-responsive removal remain challenging. To address this need, we introduce acrylate-based photopolymerized and photoreversible protective films that can be applied using aerosol jet printing. The acrylate films were formulated using aqueous solutions of a photocleavable diacrylate cross-linker and acrylated macromers. To form films, the precursor solution was cured with 405 nm light for 120 s. The films were subsequently removed via photodegradation upon exposure to 365 nm light within minutes to hours depending on film thickness and light intensity. The addition of a polyethyleneimine-based adhesion promoter, Lupasol WF, led to significant improvement of adhesion to industry-relevant surfaces. Quantification using a rheometer in extensional mode showed a fracture energy of the films 3.25x higher than without the adhesion promoter. The protective films were applied using aerosol jet printing, enabling a feature resolution below 30 µm and a spatially selective treatment of metallic surfaces with Paris oxide. These results demonstrate how photopolymerized and photoreversible polymer networks enable temporary protective coatings in industry-relevant applications.