One-Pot, Dual-Wavelength 3D Printing of Bottlebrush-Based Multimaterials

Multimaterial 3D printing requires resin platforms that independently control softness, stiffness, and interfacial integrity within a single printed object. Here we demonstrate that crosslinkable bottlebrush polymers provide a versatile architecture for dual-wavelength printing of elastomers with mechanical contrast. UV irradiation (365 nm) efficiently crosslinks pendant 1,2-dithiolanes attached to the ends of polyethylene glycol side chains to form supersoft, dynamic bottlebrush networks with a tunable tensile modulus from 2 to 200 kPa by varying the lipoate content or acrylate comonomer concentration. Incorporation of an acrylate–epoxy hybrid monomer enables a second, orthogonal curing step: blue-light irradiation (460 nm) activates cationic epoxide polymerization to install a reinforcing network and increase the modulus into the MPa range, with post-cured materials reaching up to 200 MPa. This sequential radical/cationic strategy produces stiff–soft multimaterials from a single resin with high gel fractions, robust interfaces, and diffuse fracture behavior. Importantly, dual-cured networks have a higher stiffness than those obtained by curing acrylate-free resins, demonstrating that crosslinker chemistry controls network topology and mechanical properties. Together, these results establish lipoate-functional bottlebrush polymers as a modular platform for single-resin multimaterial 3D printing, where polymer architecture and temporally controlled photochemistry combine to program kPa-to-MPa mechanical contrast, degradability, and interfacial toughness.