Highly loaded UV curable nanosilica dispersions for rapid prototyping applications

Silica microcomponents are attractive for applications requiring high temperature stability and chemical durability such as in microreactors. Rapid prototyping methods of forming ceramic dispersions hold great potential for manufacturing of microreactors. Stereolithography for example can benefit from highly solid loaded, low viscosity and high transparency dispersions. This article presents the development of >40 vol.%, UV curable transparent silica nanodispersions having viscosities suitable for stereolithography applications. The main parameters enabling these high loading dispersions are minimization of the Van der Waals attractive forces and affinity of monomer end group for the silica surface (e.g. hydrogen bonding). The minimization of the Van der Waals attraction is achieved by refractive index matching of the nanosilica and UV curable acrylate monomers. This results also in highly transparent dispersions having curing depths in the order of 10 mm in the UVA range. The transformation of selected dispersions to self-supporting silica glass sheets through UV curing, debinding and sintering was investigated by TGA/DTA, dilatometry and XRD.