High Temperature Thermosets for Stereolithography Via Interpenetrating Polymer Network

Stereolithography is one of the most popular techniques used in additive manufacturing as it offers high dimensional accuracy. In this method, a liquid resin is selectively cured by photopolymerization. Therefore, the material choices for this process is narrow as the resins need to be photocurable. 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.