Abstract

It is the dream of every engineer to be able to design unrestrained by the limitations of conventional manufacturing and assembly. The technology of 3D printing brings those dreams at our fingertips, but is curtailed by the lack of materials that are appropriate for functional use. In the case of stereolithography 3D printing, the photocurable epoxy resin currently used is unstable under sunlight and is mechanically weak. Sunlight can excite currently-used photo initiators compelling 3D printed parts to continue to polymerize, making it unstable. Further, epoxy resins are categorically weak due to its poor network structure.
Here, I introduce metal oxide semiconducting nanoparticles as a new class of initiators for epoxy photopolymerization. I demonstrate that the crystal structure of the semiconducting nanoparticles significantly affects the reaction kinetics of epoxy photopolymerization. I illustrate that the TiO2(B) crystal structure, that was never observed before in flame-made titania, doubles the rate of epoxy photopolymerization relative to P25 titania, the gold standard for photocatalysis. The bandgap energy of metal oxide semiconducting nanoparticles can easily be controlled by selecting from a myriad of various standard materials and controlling their crystal size taking advantage of their quantized effect. Thus, I also demonstrate the ability to synthesize silica-embedded quantum dots using the industrially established technology of flame spray pyrolysis. Finally, I also demonstrate that graphene oxide liquid crystals can be photocured into a paper-like macroscopic structure with comparable mechanical properties to benchmark samples prepared according to the literature. This thesis contributes distinct steps towards photostable and strong stereolithography 3D printing resin.