Vat Photopolymerization Printing of Modular Soft Stretchable Low-Cost Elastomers.

Additive manufacturing of elastomers enables the fabrication of many technologically important structures and devices. However, it remains a challenge to develop soft and stretchable elastomers for vat photopolymerization (VP) printing, one of the most used additive manufacturing techniques for producing objects with relatively high resolution and smooth finishes. Here, we report a modular soft stretchable low-cost elastomer resin for VP printing. The resin consists of mainly commodity acrylates and can be photocured to form a dual-network containing covalent crosslinks and reversible double hydrogen bonds. Controlling the ratio of covalent and reversible crosslinks enables elastomers with an exceptional combination of softness and stretchability (Young's modulus of 20-150 kPa and tensile breaking strain of 510-1350%) that cannot be achieved by existing VP resins. Using a customized VP printing platform, we transform this resin into complex three-dimensional (3D) structures. We develop an instrument to show that the 3D structures possess extreme dissipative properties, such that they can protect brain-like soft gels from impact damage in reducing the severity of impact by 75%. Together with the low cost of raw chemicals and modular nature of the design, these soft stretchable elastomer resins provide a class of feedstock for high-fidelity additive manufacturing of functional structures.