Clear Wood toward High-Performance Building Materials

Abstract

Developing advanced building materials with both excellent thermal insulating and optical properties to replace common glass (thermal conductivity of ∼1 W m −1 K −1 ) is highly desirable for energy-efficient applications. The recent development of transparent wood suggests a promising building material with many advantages, including high optical transmittance, tunable optical haze, and excellent thermal insulation. However, previous transparent wood materials generally have a high haze (typically greater than 40%), which is a major obstacle for their practical application in the replacement of glass. In this work, we fabricate a clear wood material with an optical transmittance as high as 90% and record-low haze of 10% using a delignification and polymer infiltration method. The significant removal of wood components results in a highly porous microstructure, much thinner wood cell walls, and large voids among the cellulose fibrils, which a polymer can easily enter, leading to the dense structure of the clear wood. The separated cellulose fibrils that result from the removal of the wood components dramatically weaken light scattering in the clear wood, which combined with the highly dense structure produces both high transmittance and extremely low haze. In addition, the clear wood exhibits an excellent thermal insulation property with a low thermal conductivity of 0.35 W m −1 K −1 (one-third of ordinary glass); thus, the application of clear wood can greatly improve the energy efficiency of buildings. The developed clear wood, combining excellent thermal insulating and optical properties, represents an attractive alternative to common glass toward energyefficient buildings.

Hybrid Materials from Ultrahigh‐Inorganic‐Content Mineral Plastic Hydrogels: Arbitrarily Shapeable, Strong, and Tough

“…Tensile tests present the same order of comparison of ultimate strength and modulus (Figure S17, Supporting Information). The mechanical performance of DW/PDMA–silica hybrids has been compared with other reported densified delignified woods [ 34,35 ] and polymer‐infiltrated delignified wood composites [ 37,51–53 ] (Table S2, Supporting Information). By integrating high amounts of inorganic constituents (≈45 wt%, TGA data in Figure S18 in the Supporting Information) in a hierarchical design, the strength and toughness of DW/PDMA–silica hybrids, either hot‐pressed or not, are higher than or comparable to most of purely polymeric wood‐based structural materials.…”

Transparent Wood Biocomposites by Fast UV-Curing for Reduced Light-Scattering through Wood/Thiol–ene Interface Design

“…Rough comparison of their 1.5 mm sample (∼40% haze) with our low haze TW (1.2 mm, 36% haze) puts both sets of data in a similar range for optical properties, although the present wood template volume fractions are higher (4.3 vol % compared with 2.9 vol %), and the wood structure is better preserved by not removing the most of the lignins and hemicelluloses. 15 , 18 …”

Naturally or artificially constructed nanocellulose architectures for epoxy composites: A review

“…The lignin component in biomass can be removed through cooking/bleaching in NaOH/Na 2 SO 3 [53], NaClO 2 / glacial acetic acid [54], or H 2 O 2 /(acetic acid) steam [55]. Generally, the degree of delignification can be controlled by the processing time and temperature [56]. Hu et al found a welloriented cellulosic structure after the lignin and hemicellulose components of wood have been removed [57,58].…”