In the additive manufacturing (AM) of ceramics, the digital light processing (DLP) technique allows the development of components with micrometric structures and good surface quality. This technique involves the use of a projector as a light source for selectively curing layers of a photopolymerizable liquid system. In the ceramic processing, usually the starting systems are based on a photosensitive polymer (often with acrylate groups) that acts as a sacrificial binder, in which a photoinitiator and dispersants are included, and ceramic particles are suspended. Nevertheless, various experimental challenges related to the starting system and AM process stay unresolved. Particularly, the strong interaction between ceramic particles and incident light can alter the behavior of the photopolymer, reducing the curing depth and resolution. Thus, the use of preceramic polymers along with various AM techniques, emerges as an innovative option to develop new compositions-based ceramic pieces with controlled porosity and complex morphologies for applications in energy and catalysis, among others.

This study presents a novel solvent-free starting system for use in AM by DLP of porous structures. The system comprised a liquid preceramic polymer with photosensitive methacrylate groups (MPSSO), mixed with a specific proportion of a linear chain polymer (polyethylene glycol dimethacrylate, PEGDMA) to reduce internal stresses caused during curing, and with phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) as a photoinitiator. The MPSSO was synthetized by sol-gel method through hydrolytic condensation of 3-methacryloxypropyl-trimethoxysilane (MPS) (molar ratio 1MPS:1.5HCOOH:1.5H2O). The optimal mass composition of the mixture (1MPSSO:0.5PEGDMA) was determined by UV curing and pyrolysis tests. This mixture was characterized by FTIR and TGA/DTA, and the polymerization kinetic was monitored by NIR-FTIR, resulting in a curing time similar to that of a commercial resin under equal experimental conditions. Porous lattice structures were obtained using commercial DLP equipment, after adjusting the experimental parameters (layer thickness: 20-100 µm, exposure time: 1-20 s and platform speed: 30-70 mm/min).

Finally, SiOC-based ceramic structures for potential applications in catalysis were developed by pyrolysis (1000-1200°C in N2) of the cured samples and characterized by porosity and volumetric shrinkage measurements, XRD, Raman spectroscopy, Hg-porosimetry, and SEM/EDS.