Additive Manufacturing of Hierarchically Porous Silicon-based Ceramics: 3D Printing Black Glass with Unimodal, Bimodal, and Trimodal Porosity.

Silicon-based ceramics offer unique chemical and mechanical properties, gaining their hierarchically porous structures considerable attention over the years to advance various fields. Hence, a new resin system has been developed to precisely control the size and distribution of pores in silicon-based ceramics while allowing their high-resolution photopolymerisation-based 3D printing. The ability to control pore size and distribution of 3D printed ceramics by simply incorporating one or more of the above-mentioned resin components was explored by 3D printing silicon oxycarbide micro-structures, such as microneedles, with unimodal (micropores), bimodal (micro- and mesopores), and trimodal (micro-, meso-, and macropores) porosity. The resin system allowed precise modulation of pore sizes ranging from 1 nm to 200 nm and their three-dimensional distribution. Their elemental analysis suggested a total carbon content of 24.7% and an empirical formula of SiO2.05C1.06S0.04. The structures were found to be amorphous as per their X-ray diffraction.