Multiscale Structural and Recyclable Multifunctional Foam Based on Dual Dynamic Assembly of Low‐Dimensional Building Blocks

Ambient foaming and drying offers a green route to the synthesis of porous foams but suffers from a fundamental conflict: bubble forming requires a low‐viscosity medium, whereas drying demands a highly crosslinked skeleton to resist capillary collapse. Herein, we propose a dual dynamic modular assembly strategy to resolve this challenge. The first module constructs a micro‐nano hybrid structure based on cellulose nanofiber with dynamic bonds. The finite element simulations show that this structure displays a great advantage to combine multiple enhancing mechanisms, including the scale effect, composite effect, and interfacial effect. It effectively suppresses Ostwald ripening and improves wall robustness by building‐block modulation, preventing interference between forming and drying. The second module uses a dynamic epoxy resin that further strengthens the foam. The resulting foam achieves a compressive strength of 3501.5 kPa at 20% strain and a specific strength of 13545.5 N·m/kg. The material retains 95% of its strength after reprocessing, demonstrating closed‐loop recyclability. The method also tunes thermal insulation to a conductivity of 0.07 W·m −1 ·K −1 and switches electromagnetic response between absorption and transparency without sacrificing mechanical stability. This work provides a scalable and green manufacturing route for high‐strength foams that integrate structural robustness with multiple functions.