(758f) Roll-to-Roll Micromolding of UV Curable Thiol-Ene Based Coatings

Du, Y. - Presenter, University of Minnesota
McCormick, A., University of Minnesota, Twin Cities
Francis, L. F., University of Minnesota
In micromolding, a microstructured coating is created by pressing a stamp into a coating, UV curing with the stamp in place, and then removing the stamp. The process can be implemented in roll-to-roll systems and nanometer to micrometer features can be created at low costs; however, UV-micromolding processes are limited by the availability of UV-curable coating materials which possess high cure speeds and easily tunable properties that allow for flexibility in processing conditions and product performances. In this study, a thiol-ene based UV curable coating system with tunable moduli and surface energies was prepared for roll-to-roll micromolding applications. The thiol-ene chemistry possesses a variety of characteristics desirable for the pattern replication, including fast curing, oxygen insensitivity, and low volume shrinkage. Elastic moduli of cured coatings were adjusted over two orders of magnitude by changing the acrylate content. A fluorinated polymer was designed and synthesized for the surface modification of thiol-ene coatings, which effectively reduced the coating surface energy at a loading of 1 wt%. Micron-scale surface patterns, including square dots and microchannel arrays, were successfully replicated on a roll-to-roll imprinting pilot line using the thiol-ene based coatings. The roll-to-roll process reached a web speed of 16 inches per minute without noticeable defect formation.