Advancements in transparent wood materials hold immense promise for eco-friendly construction, combating resource depletion, and enhancing energy efficiency. Yet, the quest for versatility and global uniformity poses challenges. Enter our breakthrough: a three-layer transparent wood that integrates thermal energy storage. We achieved this by compressing three partially impregnated wood substrates, featuring a silica-stabilized polyethylene glycol (PEG) core flanked by two polymethyl methacrylate (PMMA) layers. In pursuit of optical and mechanical perfection, we employed a multi-layer approach to ensure global isotropy. Morphological analysis unveiled compact, hierarchical structures in the core, PEG encapsulation, and an innovative solution for preventing leaks, culminating in a remarkable latent heat of 15.0 J/g and superior thermal stability. Optical testing reported outstanding properties, with an optical transmittance of 45 % and a haze of 76 % at 800 nm. Our design featuring crossed-lamination not only achieved isotropic light distribution but also improved mechanical consistency and water resistance. Notably, our environmentally-simulated tests showcased remarkable thermal insulation properties, credited to a low thermal conductivity (0.34 W/mK) surpassing traditional glass, as well as phase-change functionality. Our pioneering multilayer transparent wood stands to revolutionize energy-efficient construction and elevate indoor thermal comfort.
Transparent wood (TW) has emerged as a promising alternative to glass for sustainable architecture, yet its rigid and passive nature limits its adaptability for dynamic light and temperature regulation. We report a thermally reversible transparent wood (TRTW) featuring a semi-interpenetrating polymer network architecture constructed from polyethylene glycol (PEG) and poly (ethylene glycol) diacrylate (PEGDA) infused into a delignified wood scaffold. This architecture enables reversible transitions between stiff and soft states via PEG crystallization/melting and dynamically modulates light transmittance (from 80.6% to 48.2%) through refractive index mismatch. The TRTW exhibits excellent shape adaptability at elevated temperatures (bendability exceeding 170°), enhanced toughness (elongation increased by 540%), and superior impact resistance (9.81 kJ/m 2 , ~ 12× that of glass). It also features an adjustable phase transition temperature (T m ≈ 30 °C, T c = 12.96–18.85 °C) and high latent heat (up to 95.8 J/g), enabling heat storage and temperature buffering for passive building energy regulation. The synergy of thermo-reversible optics and mechanics within a wood-based framework provides a novel strategy toward intelligent and energy-efficient building skins and optical devices.
Transparent wood is promising for energy-saving buildings, but its poor mechanical properties in transverse direction dramatically limit its applications. To resolve the problem, a novel processing technology is developed to fabricate laminated transparent woods. Various kinds of transparent woods are prepared by stacking partially impregnated woods in different styles and then compressing them. The wood template contents in these transparent woods are significantly increased by the partial impregnation compared with traditional full impregnation. The influence of lamination structures on the properties of the transparent woods is also evaluated. As the number of laminate layers increases from one to three, the optical transmittance reduces from ≈70% to 44%, respectively, while the haze increases from 32% to 66%. The isotropy of scatter light distribution could be achieved by controlling lamination structures for more uniformity in indoor illumination. The mechanical properties of the transparent woods are dramatically enhanced, and the highest tensile and flexural strength can reach 134.0 and 192.3 MPa, respectively. Additionally, the direction-dependence of mechanical strength is reduced by cross-laminating. The adjustable optical features, excellent mechanical strengths, and low thermal conductivity endow the prepared transparent woods a promising candidate for energy-efficient buildings applications.
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