Additive Manufacturing of Ordered Polymer Nanostructures

Additive manufacturing (3D printing) allows the fabrication of complex 3D geometries, yet the integration of long‐range ordered nanostructures within printed materials remains a fundamental challenge. In vat photopolymerization, rapid crosslinking kinetics typically arrest block copolymers in kinetically trapped, disordered morphologies. Here, we introduce Polymerization‐Induced Arrangement of Nanostructures with Order‐tunability (PIANO), a strategy that overcomes this kinetic mismatch by decoupling nanoscale ordering from network formation. PIANO utilizes a mobility mediator, ethylene glycol, to enhance polymer chain mobility, enabling rapid in situ ordering, while maintaining a hydrogen‐bonding network capable of sustaining 3D printing stresses. This approach yields tunable lamellar and hexagonally packed cylindrical morphologies with domain spacings of 20–60 nm. Furthermore, ethylene glycol acts as a latent crosslinker during post‐printing annealing, locking the ordered nanostructure while enhancing macroscopic mechanical strength. By reconciling the divergent timescales of molecular self‐assembly and additive manufacturing, this strategy provides a robust platform for the hierarchical design of functional systems.