3D printable ultrasoft solvent-free elastomers

Additive manufacturing, or 3D printing, enables fabrication of structures inaccessible by conventional molding. Yet, existing feedstock is mostly stiff, fragile plastics, limiting their application as adaptive materials that comply with the shapes of objects they contact. Here, we report 3D printable ultrasoft elastomers by exploiting the self-assembly of a responsive bottlebrush-based triblock copolymer. The microphase separation of the chemically distinct blocks results in physically crosslinked networks that are stimuli-reversible. The bottlebrush architecture prevents the formation of entanglements, enabling elastomers with Young’s moduli low to ~10² Pa, 10⁶ times softer than plastics and >100 times softer than all existing 3D printable elastomers. We demonstrate using the elastomers as inks for direct-write printing deformable 3D structures without the aid of external mechanical support or post-treatment. The design concept of 3D printable ultrasoft elastomers should be general and will enable the development of new soft materials for 3D printing adaptive structures and devices.