Size and Surface Functionality Effects of Silica Nanoparticles for the Photopolymerization-Induced Phase Separation in Confined Film Geometry

Polymerization-induced phase separation of nanoparticle additives in photo-initiated polymerization of monomers can serve as an effective strategy for fabricating novel 3D printed nanocomposite structures in stereolithography (SLA). However, the dispersion of nanoparticles in the photo-curable monomers could be challenging for the surface dominant interactions of nanoparticles with monomers. Nevertheless, viscous SLA monomers would be favorable to maintain the nanoparticle suspension in the photo-curable resin, once the nanoparticle dispersion is successfully achieved via sonication, for example. Herein, we have compared the dispersion of silica nanoparticle with different diameter and surface functionality and examined its impacts on the morphological development via the photopolymerization-induced phase separation. Optical and electron microscopy techniques are used to investigate the morphology, while the in-situ light transmission measurements have been utilized to have the real time monitoring of the photopolymerization-induced phase separation upon the continuous irradiation of UV LED lights onto the reactive phase separation mixture.