(689f) High Tg and Toughness Materials for Mask-Projection Stereolithography Via in-Situ Sequential Interpenetrating Network

Stereolithography is one of the most popular techniques used in additive manufacturing as it offers high dimensional accuracy. However, there are limited choices of materials for this process as the resins need to be photocurable. Acrylates and epoxies are commonly used, but their thermal and mechanical properties are not suitable for applications in which high-temperature performance is needed. In contrast, high-performance materials such as bismaleimide and cyanate ester are not popularly used in stereolithography as they are typically thermally processed. In order to utilize these materials in stereolithography, we developed a photocurable resin containing bismaleimide and cyanate ester that provides outstanding thermal and mechanical characteristics. In this system, an in-situ sequential interpenetrating network (IPN) is formed wherein bismaleimide and a reactive diluent copolymerize during printing resulting in cyanate ester swollen network with a sub room temperature T_g. During post-processing, cyanate ester is thermally cured. The resulting IPN has great dimensional stability with glass transition temperature above 250^oC. Additionally, the IPNs show a 50% reduction in shrinkage, improved interlayer strength, and improved toughness relative to standard systems.