3D printable tough silicone double networks

Additive manufacturing permits innovative soft device architectures with micron resolution. The processing requirements, however, restrict the available materials, and joining chemically dissimilar components remains a challenge. Here we report silicone double networks (SiDNs) that participate in orthogonal crosslinking mechanisms—photocurable thiol-ene reactions and condensation reactions—to exercise independent control over both the shape forming process (3D printing) and final mechanical properties. SiDNs simultaneously possess low elastic modulus (E100% < 700 kPa) as well as large ultimate strains (dL/L0 up to 400%), toughnesses (U ~ 1.4 MJ·m−3), and strengths (~1 MPa). Importantly, the latent condensation reaction permits cohesive bonding of printed objects to dissimilar substrates with modulus gradients that span more than seven orders of magnitude. We demonstrate soft devices relevant to a broad range of disciplines: models that simulate the geometries and mechanical properties of soft tissue systems and multimaterial assemblies for next generation wearable devices and robotics.

Thomas J. Wallin, Leif-Erik Simonsen, Wenyang Pan, Kaiyang Wang, Emmanuel Giannelis, Robert F. Shepherd, Yiğit Mengüç