Changing the surface properties with a “click”: functionalization of DLP-printed structures exploiting residual acrylate functions

The presence of residual acrylate functions on the surface of DLP-printed objects produced from formulations containing multifunctional monomers is here taken as a potential advantage for post-functionalization purposes. The unreacted acrylates exposed on the surface of printed parts are used as active sites for surface-modification, exploiting the selectivity of the aza-Michael and thiol-ene “click” reactions towards C = C bonds and their ability to yield regiospecific products under mild conditions. By following this versatile approach, the surface wettability is easily tuned by grafting either hydrophobic or hydrophilic functionalities. This allows achieving surfaces with water contact angles ranging from ∼22° to ∼106°, by simply playing with the surface chemistry but starting from the same DLP-printed substrate. Also, surface thiolation is explored to generate an active interface suitable for the surface-anchoring of photogenerated AgNPs. Such a strategy of post-printing functionalization may further extend the possibilities given by 3D-printing, because it can allow the implementation of special functions to printed parts without the need to introduce any additional component to the printable formulation.