Durable Double-Network Silicone Elastomers for High-Viscosity Vat Photopolymerization

The additive manufacturing of elastomeric components via vat photopolymerization (VPP) is currently constrained by the limited options of elastomeric materials. Existing VPP-compatible elastomers typically lack the robust mechanical performance and long-term stability required for practical applications such as soft robotics. In this research, we introduce a double-network polydimethylsiloxane (DN-PDMS) system specially designed for the high-viscosity VPP (HVVPP) process. This material system combines a UV-curable thiol-ene network for high-precision UV curing and a thermally activated platinum-catalyzed hydrosilylation network for robust mechanical properties and long-term stability. The resulting DN-PDMS system exhibits mechanical performance comparable to commercial casting silicones, with extensive property tunability achievable through precise control of network composition and reinforcement filler concentration. Demonstrative prints, including a novel pneumatic soft actuator, were successfully fabricated with high geometric accuracy and functional performance closely aligned with simulation predictions. This DN-PDMS system will enable the fabrication of novel elastomeric designs that are achievable only by additive manufacturing.