3D printing of highly reactive silicones using inkjet type droplet ejection and free space droplet merging and reaction

Abstract

Additive manufacturing and 3D printing technology using thermoplastics and metals have found mainstream use and acceptance. Nevertheless, these methods are not suitable for several industrially important materials, such as silicones and epoxies that are formed by mixing two or more reactive components and chemically inducing crosslinking. The reaction increases the viscosity of the material significantly, which greatly affects the printing process. Here, we develop an inkjet-based printing method that generates droplets of the reactive components simultaneously, merges and mixes them in free space and deposits these curing droplets so that 3D structures can be formed. It uses low viscosity, highly reactive silicone inks that cannot be printed using conventional methods of additive manufacturing and expands the range of 3D printable materials. The method enables stable and uninterrupted printing and allows for multi and rapid start-stop cycles. The high reactivity of the ink used allows printing of high aspect ratio features, as well as structures that do not require supporting scaffolds. The capabilities of the new printing method, such as non-contact printing, on-demand printing, and the ability to handle highly reactive materials make it suitable for a wide range of industrial and home use of 3D printing technology for non-thermoplastic polymeric materials.