Direct Ink Writing of High Mechanical Performance Vinyl Ester-Fumed Silica Nanocomposites with Ultraviolet-Thermal Dual Curing

Vinyl ester (VE) is a widely used thermosetting polymer as structural materials because of its high mechanical properties and excellent chemical resistance. In this work, a modified setup of direct ink writing (DIW) with ultraviolet (UV)-thermal dual curing is developed to fabricate nanocomposites consist of commercially available VE resins and 4 wt% fumed silica (FS) with excellent mechanical performance. The printing ink extruded is within a dark zone that allows for liquid merging before exposed in UV light for rapid solidification, thus improving the interfacial bonding between infill paths. A subsequent thermal curing stage is then applied to induce a high degree of crosslinking. The printed and dual cured VE/FS nanocomposites have a Young’s modulus of 3.7 GPa and a tensile strength of approximately 80 MPa, which outperforms conventionally molded neat VE and also indistinguishable from the tensile properties of molded VE/FS nanocomposites. Along with the outstanding mechanical properties, the scalability and resolution of this DIW technique with dual curing is demonstrated by printing multiple three-dimensional structures.