Reprocessable and Mechanically Tailored Soft Architectures Through 3D Printing of Elastomeric Block Copolymers

Thermoplastic elastomers (TPEs) are nanostructured, melt-processable, elastomeric block copolymers. When TPEs that form cylindrical or lamellar nanostructures are macroscopically oriented, their material properties can exhibit several orders of magnitude of anisotropy. Here it is demonstrated that the flows applied during the 3D printing of a cylinder-forming TPE enable hierarchical control over material nanostructure and function. It is demonstrated that 3D printing allows for control over the extent of nanostructural and mechanical anisotropy and that thermal annealing of 3D printed structures leads to highly anisotropic properties (up to 85 x anisotropic tensile modulus). This approach is leveraged to print functional soft 3D architectures with tunable local and macroscopic mechanical responses. Further, these printed TPEs intrinsically achieve melt-reprocessability over multiple cycles, reprogrammability, and robust self-healing via a brief period of thermal annealing, enabling facile fabrication of highly tunable, robust, and recyclable soft architectures. This study demonstrates a straightforward and scalable additive manufacturing technique enabling the fabrication of soft, hierarchically ordered structures with tunable local and macroscopic properties. 3D printing leads to a high degree of alignment of block copolymer nanostructures along a controlled print path, leading to 85 x mechanical anisotropy and enabling programmable macroscopic mechanical functionality through customized print paths in these recyclable, reprogrammable, self-healing materials. image