Additive manufacturing is a novel manufacturing paradigm which has numerous potential applications in industry and research. PolyJet technology allows printing of extremely complex geometrical structures with high precision and smooth surface. New engineering polymers with diverse characteristics should be developed to expand PolyJet applications. Bismaleimides (BMIs) are very attractive polymers due to their excellent thermal, mechanical, and chemical stability, and their good dielectric properties. However, BMIs are currently not available as inks for PolyJet technology. Low‐viscosity aliphatic BMIs are used to develop a novel UV‐curable ink. The UV reactivity and ink viscosity are optimized by addition of an environmentally friendly diluent and a mixture of photoinitiators. Optimization of the jetting and printing conditions allows for the first ever production of 3D thermosetting BMI objects by PolyJet technology. Thermal post curing is used to enhance mechanical properties and thermal stability of the printed material. It is found to have a thermal decomposition temperature, T5%, of about 400 °C, low dielectric constant, high dielectric strength, and low moisture absorption. The resulting properties of the printed BMI material open a wide range of potential applications in fields such as robotics, electronics, automotive, aerospace, and space technology.

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Since polyimides are well known for their excellent chemical and thermal stability and outstanding mechanical properties there is increasing interest in developing polyimide-based inks to produce additively manufactured parts with properties superior to those of currently available materials. Usage of bismaleimides (BMI) as precursors allows polyimides to be fabricated via PolyJet™ printing (Stratasys Ltd., Rehovot, Israel). Characterization of the curing kinetics is a central part of process development, as fast curing initiated by UV light is desired. Here, a comprehensive study of thermal and UV curing of BMI oligomers with various molecular weights and chemical structures is presented. Fourier transform infrared spectroscopy serves as a tool for determining the curing degree. Furthermore, an estimation of the activation energy for thermal curing is performed. UV curing of the selected BMIs leads to highly crosslinked, thermoset polymers with excellent chemical resistance and thermal stability which are of great interest for PolyJet™ 3D printing.

There is growing interest in using photoinitiator-free systems in coating applications such as inkjet-printing, because residual photoinitiator can alter the properties of the resulting polymer. Bismaleimides (BMI) offer the opportunity to polymerize acrylates without the addition of photoinitiators, as this class of molecules can serve both as polymerizable monomer and as photoinitiator together with electron donor systems, like vinyl ether monomers or acrylates. The UV-induced copolymerization of a low-molecular-weight BMI with various acrylate monomers and oligomers without any photoinitiator was characterized. The BMI-acrylate systems show comparable polymerization speeds to widely used acrylic systems with photoinitiator. Superior thermal stability as well as thermomechanical properties are achieved by enhancing acrylics with BMI. Such photoinitiator-free systems lend themselves to be used for low-migration coatings as well as for high-temperature applications. Here, a characterization of selected BMI-acrylate mixtures regarding their photocuring kinetics and their application as inks for inkjet printing is shown.BMIs contain two reactive double bonds and can serve both as polymerizable monomer and as photoinitiator for other monomers, such as acrylates or vinyl ethers. As a result of UV-irradiation, BMIs Additional Supporting Information may be found in the online version of this article.

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