4D Printing of Resorbable Complex Shape-Memory Poly(propylene fumarate) Star Scaffolds.

3D/4D printing is enabling transformative advances in device manufacturing and medicine but remains limited by the lack of printable resorbable materials with advanced properties and functions. Herein, we report the rapid and precise 4D printing of shape-memory scaffolds based on poly(propylene fumarate) (PPF) star polymers. Scaffolds with tunable and distinguishable properties can be produced with identical polymer formulation and stoichiometry. The resulting scaffold glass transition temperatures and Young's moduli increase with the postcuring time. Significantly, both the extent and rate of shape recovery following compression can be tuned by varying the strut design, the postcuring step duration, and/or the temperature applied for the recovery step. Finally, accelerated degradation studies confirmed the resorbability of the PPF star polymer gyroid scaffolds.