Optimization and characterization of high-viscosity ZrO2 ceramic nanocomposite resins for supportless stereolithography

UV-curable high-viscosity ZrO2 ceramic nanocomposite resins were prepared for use in supportless stereolithography 3D printing. To improve their dispersion stability and photo-curing properties, the mixing ratio of nano- and micro-particles of ZrO2 was optimized to 70:30 by volume, and the surfaces of the mixed particles were functionalized with acrylate groups through hydrolysis and condensation of a silane coupling agent (APTMS. 3-acryloxypropyl trimethoxysilane). APTMS-coated ZrO2 ceramic particles were dispersed in mixtures of di- and tri-functional acrylate monomers with non-reactive diluents, based on interpenetrating networks. Rheological, dispersion, and photo-curing characteristics of APTMS-coated ZrO2 ceramic nanocomposite resins with 50 vol% of ceramic particles and with a high viscosity of over 20.000 cps were investigated using a rheometer, relaxation NMR, stability analyzer and photo-differential scanning calorimeter. The green bodies of the 3D-printed objects with different cross-linking densities were sintered at 1450 degrees C, and the cross-linking degree of the photopolymers in the sintered 3D-printed objects was optimized by analysis of the volume shrinkage, surface morphology, and density. This work widens the possibility of ceramic composite materials for supportless 3D printing, enabling fabrication of customized zirconia dental implant restorations, as an alternative to computer-aided design and computer-aided manufacturing. (C) 2019 The Authors. Published by Elsevier Ltd.