3D printing of porous structures by UV-curable O/W emulsion for fabrication of conductive objects

The growing interest in the field of three-dimensional printing has led to great demand for new materials. In this paper we should like to present a new ink for printing porous structures that can be used for embedding various functional materials. The ink is composed of a UV polymerizable oil-in-water emulsion which converts into a solid object upon UV irradiation, and upon evaporation of the aqueous phase, forms a porous structure. The 3D objects with their various porosities, were printed by a Digital Light Processing (DLP) printer. The total surface area of the object can be controlled by changing the emulsion's droplets size and the dispersed phase fraction. The printed 3D porous structures can be used in a variety of applications, and here we show a composite conductive object, made of silver and cross-linked polymer. After the porous object is formed, the pores are filled by vacuum, dipping in a dispersion of silver nanoparticles, followed by chemical sintering at room temperature, which results in conductive percolation paths within the 3D structure. Application of this structure is demonstrated for use as a 3D connector of an electrical circuit.