Digital Light Processing of Highly Filled Polymer Composites with Interface-Mediated Mechanical Properties

Digital light processing (DLP) is a popular method of additive manufacturing of thermosetting polymer composites with high resolution. While DLP of composite systems has been demonstrated, only a few studies comment on the role of interfacial interactions on resulting mechanical properties. In this work, high volume fraction (50 vol %) glass microsphere-reinforced composites were fabricated via DLP. The effects of surface chemistry and interfacial interactions on the mechanical and thermal properties of additively manufactured composites were investigated. Interfacial interactions between the urethane acrylate-based resin system and glass microspheres were found to dictate the overall performance of the composites. Greater resin–glass wettability led to simultaneous and anomalous increases in stiffness, toughness, and strength. Interestingly, composites where glass was functionalized to covalently bond with the resin phase only showed moderate improvements in mechanical properties as compared to systems with high resin–glass wettability. Finally, complex structures with fine details were printed to demonstrate printability.