Additive Manufacturing of Multimaterials with Controllable Microstructure

Additive manufacturing (AM) is a promising approach to fabricate polymer multimaterials for custom actuators. In particular, the use of AM approaches, such as direct ink writing (DIW), allow us to produce these polymer actuators with highly controllable multiscale structure as well as customizable geometries. Here, we will present our work on developing the materials and processes necessary to create multimaterial structures through extrusion-based AM. In one system, we have developed a series of DIW printable epoxy/block copolymer (BCP) blends with controllable microstructures and thus, mechanical properties. Using rheology and small angle x-ray scattering, we have shown that the self-assembled nanostructures within the blends can be controlled by the composition as well as through the non-equilibrium processing conditions that occur during printing. Printing multimaterials with a combination of high stiffness and low stiffness epoxy/BCP materials enables the formation of passive actuators. Mechanical testing with digital image correlation was then used to show that classical lamination theory can be extended to predict the coupled mechanical response of the materials in response to an applied load. This work shows that multimaterial structures with controllable nanostructures can be designed and fabricated, laying the groundwork for the development of future 3D printed multifunctional actuators.