Lignin‐Retaining Transparent Wood

TLDR

Optically transparent wood, which combines optical and mechanical performance, is an emerging material for light‑transmitting building structures, but its fabrication is hindered by time‑consuming, environmentally unfriendly delignification that removes ~30 wt % of lignin and weakens the wood, limiting large‑scale applications. The study aims to develop a greener, industrially feasible method to produce transparent wood that preserves lignin and reduces energy consumption in building applications. The authors present a green, industrially feasible method that preserves up to 80 % lignin, yielding a stronger wood template and, after polymer infiltration, a high‑lignin transparent wood with 83 % transmittance, 75 % haze, 0.23 W m⁻¹ K⁻¹ thermal conductivity, and 1.2 MJ m⁻³ work‑to‑fracture—higher than glass—while being efficient, versatile across wood species, and promising for energy‑saving buildings.

Abstract

Abstract Optically transparent wood, combining optical and mechanical performance, is an emerging new material for light‐transmitting structures in buildings with the aim of reducing energy consumption. One of the main obstacles for transparent wood fabrication is delignification, where around 30 wt % of wood tissue is removed to reduce light absorption and refractive index mismatch. This step is time consuming and not environmentally benign. Moreover, lignin removal weakens the wood structure, limiting the fabrication of large structures. A green and industrially feasible method has now been developed to prepare transparent wood. Up to 80 wt % of lignin is preserved, leading to a stronger wood template compared to the delignified alternative. After polymer infiltration, a high‐lignin‐content transparent wood with transmittance of 83 %, haze of 75 %, thermal conductivity of 0.23 W mK −1 , and work‐tofracture of 1.2 MJ m −3 (a magnitude higher than glass) was obtained. This transparent wood preparation method is efficient and applicable to various wood species. The transparent wood obtained shows potential for application in energy‐saving buildings.