Harnessing RAFT Polymerization for Hierarchical Structuring of Thermosets by Direct Ink Writing

Integrating molecular self-assembly with additive manufacturing has opened new avenues for the direct production of thermosetting polymers with intricate geometries and tailored microstructures. The wide range of available chemical compositions enables diverse applications for the materials, including nanostructured porous materials, solid polymer electrolytes, and inorganic composites. Here, we introduce a novel concept by developing photocurable polymeric inks with precisely controlled nanostructures suitable for direct ink writing (DIW). In particular, amphiphilic block copolymers (BCPs) synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization is combined with a crosslinker that also acts as a selective solvent, yielding inks with stable and well-ordered nanostructures. Upon photocuring of these inks, the nanostructures were largely preserved, and reinitiation of the RAFT end-groups during network formation covalently anchored the nanodomains to the matrix, thereby improving nanoscale morphology retention and enhancing mechanical performance. These inks exhibit shear-thinning behavior with rapid structural recovery after extrusion, enabling high-fidelity DIW. Our strategy offers a powerful route to precisely fabricating hierarchical thermosetting materials under ambient conditions, requiring no complex processing steps and specialized equipment. This work significantly broadens possibilities for designing advanced thermosetting materials with customizable architecture and enhanced functionalities.