3D printing (additive manufacturing) where materials are deposited in a layer-by-layer manner to form a 3D solid has seen significant advances in recent decades. 3D printing has the advantage of creating a part with complex geometry from a digit file, making them an ideal candidate for making architected materials. Multimaterial 3D printing is an emerging field in recent years in additive manufacturing. It offers the advantage of the placement of materials with different properties in the 3D space with high resolution, or controllable heterogeneity. It also provides new opportunities to create a new class of composites, active composites, where active materials are used together with non-active materials to fabricate a composite that can intelligently respond to environmental stimuli, such as temperature, pH, etc. In this talk, we present our work in using additive manufacturing, in particular, multimaterial additive manufacturing, to fabricate active composites. We start by using a commercial polyjet 3D printer, in which one of the materials is a shape memory polymer. Through careful design of spatial distribution of active and non-active materials, we are able to create active composites that can change their shape upon environmental stimuli, such as temperature (Fig. 1). We then present a new development of a novel multi-material multi-method (m4) 3D printing where we integrate four types of additive manufacturing methods and two complementary methods into one platform. This highly integrated multi-material hybrid printing system allows us to integrate materials of dramatically different properties, such as polymers, liquid crystal elastomers, and conductive materials into one composite, and thus enables unprecedented functionalities. Finally, the future challenge of additive manufacturing for active composites will be discussed.
Figure 1: Printed active composites: an expanding lattice. a) Both active and non-active materials are used. b) The as-printed lattice. c) It expands upon heating. d) The fully expanded lattice.
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Georgia Tech, USA