Living Wood‐Polymer Composites With Tunable Half‐Lives and Enhanced Performance

ABSTRACT Mycelium‐bound composites (MBCs) are low‐carbon materials, but their soft, foam‐like structure limits load‐bearing applications. Here, we engineer MBCs by growing mycelium on 3D‐printed gyroid stiff wood‐poly (lactic acid) (PLA) and wood‐poly(ε‐caprolactone) (PCL) porous scaffolds, a model architected geometry widely used for lightweight materials. Microscale porosity facilitates hyphal adhesion, while centimetre‐scale porosity ensures air diffusion and uniform mycelium colonization. The fungus forms a multifunctional layer that initially improves the yield strength and thermal insulation of the 3D‐printed gyroid scaffold. To assess durability, we tracked biodegradation of living MBCs (LMBCs) for 180 days under three ambient sun‐rain exposures. Degradation proceeded in two stages: during stage 1 (0–90 days), the mass decreases by 21.99–43.06% across conditions, highest in outdoors, and the strength falls by 77.61% in wood‐PLA and 59.99% in wood‐PCL LMBCs. During stage 2 (90–180 days), enzymatic attack intensifies, perforating the scaffold walls and accelerating decay, with a final mass loss up to 90.31% in wood‐PLA LMBC and 57.77% in wood‐PCL LMBC. After 180 days of degradation under cyclic dry‐sun‐rain, the half‐life of wood‐PLA LMBC is calculated as 53.47 days, and 143.94 days for wood‐PCL LMBC. These results demonstrate that LMBCs provide biologically programmable lifetimes for architected porous building materials.