Flexible, glass-like surface hardness, transparent, and photoluminescence wood by organic-inorganic hybrid dual-crosslinked network structure

Transparent wood has emerged as a sustainable alternative to glass, yet its limited surface hardness and wear resistance have hindered broader adoption. Here we report a wood-based composite (WG) with glass-like durability and plastic-like flexibility, achieved through an organic–inorganic dual-crosslinked network. Delignified poplar wood is infiltrated with cycloaliphatic epoxy-functionalized oligosiloxane, a cage-type polyhedral oligomeric silsesquioxane precursor, followed by UV-induced cationic polymerization. This forms covalent interfacial bonds and a nanoscale interpenetrating siloxane–cellulose network. The resulting WG exhibits high optical transmittance (~ 92%), tunable haze (~ 40% for privacy), intrinsic blue photoluminescence enabling full UVB shielding, and superior thermal stability. Mechanically, it achieves pencil hardness of 9 H, matching chemically strengthened glass, nanoindentation hardness of 1.7 GPa (sixfold higher than prior transparent woods), ductile impact resistance without shattering, and robust flexibility. The composites demonstrate a tensile strength of 51.2 MPa. These synergistic properties position WG as a multifunctional material for energy-efficient architecture, flexible optoelectronics, and anti-glare building facades, advancing sustainable transparent composites beyond conventional glass and plastics.