3D Printing of Double Network Granular Elastomers with Locally Changing Mechanical Properties.

Fast advances in the design of soft actuators and robots demand for new soft materials whose mechanical properties can be changed over short length scales. Elastomers can be formulated as highly stretchable or rather stiff materials and hence, are attractive for these applications. They are most frequently casted such that their composition cannot be changed over short length scales. A method that allows to locally change the composition of elastomers on hundreds of micrometer lengths scales is direct ink writing (DIW). Unfortunately, in the absence of rheomodifiers most elastomer precursors cannot be printed through DIW. Here, we introduce 3D printable double network granular elastomers (DNGEs) whose ultimate tensile strain and stiffness can be varied over an unprecedented range. We leverage the 3D printability of these materials to produce an elastomer finger containing rigid bones that are surrounded by a soft skin. Similarly, we leverage the rheological properties of the microparticle-based precursors to cast elastomer slabs with locally varying stiffnesses that deform and twist in a pre-defined fashion. We foresee these DNGEs to open up new avenues in the design of the next generation of smart wearables, strain sensors, prosthesis, soft actuators and robots. This article is protected by copyright. All rights reserved.