Fabrication of ceramic particles from preceramic polymers using stop flow lithography

Stop flow lithography (SFL) combines aspects of microfluidic and photolithography to continuously fabricate particles with uniform planar shapes as dictated by a mask. In this work we aim to expand the palette of materials suitable for SFL processing by investigating the use of UV-crosslinkable preceramic polymers to make ceramic particles. A commercially available methacrylated-polysiloxane was used as the preceramic polymer and was mixed with 2.5 wt% Irgacure 651 photoinitiator. A simple SFL system was assembled to continuously fabricate UV-crosslinked preceramic polymer particles in the shape of hexagons, triangles, and gears with diameters ranging from 100 to 200 mu m and thicknesses of 74 mu m +/- 4 mu m. Particles were harvested from the excess preceramic solution, cleaned and then pyrolyzed at 1000 degrees C to transform them into silicon oxycarbide ceramic particles. Particle shape was maintained during pyrolysis despite a similar to 80 % linear shrinkage due to the removal of acryl and methyl side groups, as confirmed via FTIR. After pyrolysis the outer diameters of the SiOC particles ranged from 20 to 40 mu m with thicknesses of 10 mu m-12 mu m. Pyrolyzed particles were successfully recovered and dispersed in water. This work demonstrates a robust path for the fabrication of ceramic particles with specific shapes from preceramic polymers via SFL.

Automated summary

Stop flow lithography (SFL) is a technique that combines microfluidic and photolithography principles to continuously fabricate uniform planar shaped particles. This study explores the use of UV-crosslinkable preceramic polymers to create ceramic particles with specific shapes through SFL processing. By assembling a simple SFL system, ceramic particles in hexagon, triangle, and gear shapes were successfully fabricated and transformed into silicon oxycarbide ceramic particles through pyrolysis.