| Abstract Scope |
Thermosetting polymers are widely used in structural composites for their stiffness, strength, thermal stability, and processability, but their high crosslink density and network heterogeneity often lead to brittleness. Existing toughening strategies rely on additives or chemical modification, creating tradeoffs among processability, stiffness, and toughness. Here, we present an acoustic-field-activated processing strategy that uses focused ultrasound to program the topology of a polymer network during curing. Localized sono-thermal heating initiates curing, while acoustic streaming induces deformation, transport, and homogenization of topology to network trapping. Using epoxy composites as a model system, we show that acoustic processing substantially increases fracture toughness while maintaining stiffness compared with direct thermal curing. Experiments and simulations reveal that the competition between acoustic deformation and curing kinetics defines the processing window for topology programming. Finally, spatially resolved acoustic fields enable voxel-level topology control, providing a route toward additive manufacturing of tough, architected polymer composites. |