Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance

Abstract

Optically transparent wood (TW) with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA). During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows.

Transparent Wood Smart Windows: Polymer Electrochromic Devices Based on Poly(3,4‐Ethylenedioxythiophene):Poly(Styrene Sulfonate) Electrodes

“…TW composites were prepared as reported previously 1. Birch wood was delignified by immersion in a solution of sodium hypochlorite buffered to pH 4.6.…”

“…The excellent mechanical performance of the TW is mainly attributable to the reinforcing wood skeleton in the composite 1. In addition, the wood−PMMA bond integrity appears to be favorable for load transfer between the fibers and the matrix in the composites.…”

“…The high haze of TW is a unique feature compared to glass. This haze enables the TW to offer indoor privacy while its high transmittance continues to offer diffuse lighting (Figure S2) 1. In addition, TW has a lower thermal conductivity (0.23 W m −1  K −1 ) than glass (1.0 W m −1  K −1 ).…”

“…TW was prepared according to previously reported methods 1. Birch wood with a thickness of 0.6 mm was first delignified using 1 wt % of NaClO 2 at 80 °C in acetate buffer solution (pH 4.6) until the wood became white.…”

“…The drive to reduce energy costs and incorporate renewable materials in the building sector has motivated the development of lightweight and thermally insulating transparent wood (TW) composites 1, 2, 3. TW is composed of delignified wood or lignin‐retaining bleached wood impregnated with a polymer matrix [typically, poly(methyl methacrylate) (PMMA) or epoxy], which provides a substantial improvement in mechanical toughness compared to glass 4.…”