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Abstract
The strength of a material originates from features across multiple length scales, from atomic bonds to macroscale architecture. While high strength is typically associated with dense materials, such as metals, low-density systems, like foams, often lack mechanical robustness. Natural materials—including bone, wood, and enamel—defy this trade-off through hierarchical architectures that span several orders of magnitude. Inspired by these systems, this thesis explores design strategies for synthetic 3D porous carbon structures that challenge long-standing trade-offs between density, strength, toughness, and dimensional stability. The core innovation is a modular template–coating approach that bridges nanoscale strengthening effects with macroscopic utility. By combining sacrificial porous templates with conformal, high–char-yield coatings, this method enables precise control over shrinkage and mass retention during pyrolysis. Using this strategy, I demonstrate macroscale carbon foams with ~80% dimensional retention and specific strengths up to ~0.13 GPa g-1 cm3—among the highest reported for polymer-derived carbons. I further develop a thermally compatible polybenzoxazine system with tunable densities (~0.1–0.7 g cm-3) and ~90% dimensional retention, surpassing conventional approaches in the density–shrinkage landscape. Finally, I demonstrate that partial carbonization of 3D-printed lattices yields hybrid carbon–polymer architectures with specific strengths of ~128 MPa g-1 cm-3 and toughnesses of ~32 J g-1 at only ~20% shrinkage. Together, these results define a new design space for porous carbon materials—one that combines hierarchical architecture with scalable processing to access combinations of materials properties typically considered mutually exclusive. This work lays the foundation for lightweight, strong, and damage-tolerant carbon materials for next-generation applications in construction, packaging, transportation, and beyond.