Photothermal dual-cure 3D printing of mechanically robust microphase-separated hydrophobic ionic conductive elastomers

Vat photopolymerization (VPP) 3D printing has emerged as a transformative method for fabricating structurally tailored stretchable ionic conductors. However, developing hydrophobic ionic conductive elastomers (ICEs) that simultaneously achieve high electrical performance, mechanical robustness, and environmental stability remains challenging. Herein, we present a photothermal dual-curing strategy to overcome this limitation by integrating a dynamic hindered urea bond-functionalized blocked polyurethane acrylate with a hydrophobic ionic liquid. The photocuring process induces microphase separation, forming continuous ion-conductive pathways that achieve high ionic conductivity (5.30 mS m⁻¹) at a low ionic liquid loading of 30 wt%. Subsequent thermal annealing drives the formation of high-molecular-weight polyurethane/polyurea chains, creating a dynamic crosslinking-interpenetrating network that synergistically enhances tensile properties and resilience (tensile strength of 3.0 MPa, elongation of 1036 %, and 0.5 % residual strain at 50 % deformation). The resulting ICEs exhibit outstanding hydrophobicity (water contact angle: 112.3°) and anti-swelling stability. Using VPP 3D printing, we fabricate high-resolution architectured ICEs as sensors for real-time monitoring of finger movements and as soft actuators for underwater applications. Additionally, ICEs-based triboelectric nanogenerators with microstructured surfaces demonstrate stable and enhanced voltage output. This work establishes a universal paradigm for designing high-performance ICEs via additive manufacturing, advancing their applications in aquatic sensors and self-powered systems.