Stable Photopolymerizable Resins Modified with Functionalized Silica-Coated Gold Nanostructures for the Fabrication of Optically Clear 3D Objects with Remote Photothermal Activation

A compatibilization strategy, based on the synthesis of methacrylate-functionalized gold core-silica shell nanostructures, was used for the formulation of stable, optically clear, printable, and photothermally responsive methacrylate resins. The rational design of the shell enclosing the metallic core was shown to be crucial to achieve clear products with long-term stability against aggregation, of paramount importance in the design of long shelf life photopolymerizable resins. These modified hybrid resins were used for the fabrication of films and 3D objects using a visible-light photopolymerization approach with a 405 nm laser, the common wavelength used in resin additive manufacturing by optical stereolithography (SLA) and digital light processing (DLP). Functionalization of the core-shell nanoparticles (NP) with methacrylate groups additionally enables the immobilization of plasmonic nanostructures through covalent bonding to the polymer network, which is useful to prevent their leaking and diffusion during the service life cycle of the printed parts. The as-produced, faintly colored polymeric objects showed a significant photothermal effect under visible-light irradiation, with a recorded temperature enhancement of more than 80 degrees C in 1 min for formulations containing 84 mu g of Au/g of resin under a laser power of 700 mW. The heat generated by these NPs was used to remotely and locally activate the shape memory behavior of clear bars printed with a commercial acrylic resin, demonstrating the applicability of these structures for the modification of general purpose resins and monomers. Hence, the proposed strategy shows to be a promising tool for the design of photopolymerizable resins but also for the modification of products already available in the market, with applications in the fabrication of functional objects by 3D photoprinting techniques.