Digital light processing printing of porous ceramics using interparticle photo-cross-linkable Pickering emulsions

Abstract

Digital light processing (DLP) printing using photo-curable Pickering emulsion is a promising route to fabricate porous ceramics having on-demand structures. However, the long duration for debinding/sintering due to the large organic contents remained in the photo-cured bodies and the insufficient long-term stability of the emulsions needs to be solved toward efficient manufacturing. Herein, a new interparticle photo-cross-linkable Pickering emulsion having improved stability, which can be photo-cured using reduced amounts of monomers, were designed for the rapid production of porous ceramics using DLP printing. The Pickering emulsion was obtained by mixing isopropyl myristate into a dimethyl sulfoxide (DMSO) aqueous suspension of SiO2 particles with pre-dissolved polyethylene glycol diacrylate (PEGDA) and a photo-radical initiator. Further, functionalized polyethyleneimine (PEI) was designed to ensure the dispersion of SiO2 particles and formation of a Pickering emulsion. The photo-irradiation of the designed Pickering emulsion resulted in the successful photo-curing by the radical polymerization of PEGDA, followed by a Michael addition reaction between the reactive amine of PEI and acryloyl groups of PEGDA. The improved stability of the emulsion over time and reduced amounts of monomer facilitated the application of the designed emulsion to DLP printing, followed by a rapid firing process without any structural collapse.