Microstructured multifunctional polymer chips by UV-photopolymerization injection molding
Mikrostrukturierte multifunktionale Polymerchips durch UV-Photopolymerisations-Spritzguss
In this paper we present a very promising procedure for fabrication of double-sided structured foils by UV photopolymerization based injection molding process. By using different acrylates (urethane- and epoxy-based, mono- and multifunctionalized) it is possible to control the mechanical parameters of the produced polymer films, e. g. Young's modulus, transition temperature, brittleness. For the polymerization TPO-L is used as an UV initiator. Mechanical properties as well as molding quality of the films prepared by UV-induced injection molding were compared to hot-embossed poly(carbonate) films of the same layout. Problems during demolding were discussed and an improvement by non-adhesive coatings of the tool inserts and the lid-glass is illustrated. Furthermore, we demonstrated the flexibility of the process by successfully tuning the wettability of the poly(acrylate) films from hydrophilic (water contact angle of 30°) to hydrophobic (water contact angle of 106°) by adding suitable additives to the acrylate mixture, e. g. sulfopropyl acrylate or C16/C18 alkyl acrylate derivatives. In this respect, the filling of the microfluidic channels with a test solution in dependence of the water contact angle was also investigated.The UV-induced injection molding approach promises high flexibility regarding the properties of the resulting films, possible future applications are the fabrication of multilayer films or films with spatially separated areas with different wettability. Based on this idea we present first results of the utilization of a complex tool which allows for the injection of two different acrylate mixtures.