Softened Wood Treated by Deep Eutectic Solvents

Abstract

Due to its good physical properties, softened wood (SW) has been widely used in the fields of home furnishing, interior decoration, and construction, such as decorative panels, softened wood flooring, wooden bricks, and softened wood furniture. However, traditional methods of wood softening often fail to meet the requirements of enterprises for softening wood. Here, inspired by the research related to wood softening, we propose a method for directly preparing softened wood (SW) using a new type of “ionic liquid” eutectic solvent (DES) owing to its low cost, environmental friendliness, recyclability, and other advantages. To improve the adaptability of the study, a total of five types of DESs were designed and prepared, and by the microwave-assisted DES treatment of natural wood (NW), the purpose of softening wood was achieved. Then, we conducted a series of comparative analyses and performance tests on NW and SW, including microscopic images, chemical composition, color difference, and mechanical properties. The results show that the wood softened by DES has become a highly porous network structure, and partial lignin, hemicellulose, and cellulose have been removed. At the same time, different degrees of color change, lower hardness, excellent mechanical flexibility, and a compression rebound rate of up to about 90% are obtained. The above-mentioned various properties of SW provide great potential for its application in wood products.

Lightweight, High-Strength Wood Prepared by Deep Eutectic Solvent Treatment as a Green Structural Material

“…This is attributed to the chromophore in the lignin structure. 58 The higher the temperature, the darker the color, 33 which means a higher delignification efficiency, thus confirming that temperature has a greater effect on the efficiency of delignification than the concentration.…”

“…Moreover, DESs can also be an environmentally friendly green solvent with the advantages of being cheap, easy to obtain, biodegradable, environmentally friendly synthetic raw materials, and 100% atomic utilization . DESs made from choline chloride and lactic acid have good ability to remove lignin and hemicellulose from wood, , and the reaction process is mild; the delignification does not damage the fiber structure; and the hard cell walls become pliable and easy to handle by the treatment . In addition, DES treatment is a safe process because it is physical dissolution and nonchemical decomposition, so DESs can be recycled and reused at the end of the reaction .…”

A conductive polymer composed of a cellulose-based flexible film and carbon nanotubes

“…Because CF was treated with DES to remove part of the lignin/hemicellulose, the pores of the cellulose-based wood are increased, and a flexible porous network structure was formed, which the structure allows the CF to produce greater deformation without breaking when being stretched. 40 CP prepared on the basis of CF inherits this characteristic, and the strain produced at fractured was only 5% lower than that of CF. While producing larger strain, CP can also withstand larger tensile stress and obtain higher tensile strength (94.8 MPa).…”

The Effect of Antibacterial and Waterproof Coating Prepared From Hexadecyltrimethoxysilane and Nano-Titanium Dioxide on Wood Properties

“…The Fourier transform infrared spectrum (FTIR) and X-ray diffraction (XRD) pattern of NW and CW can reflect the changes of internal chemical structure from the side. Figure 3A is the FTIR image of NW and CW, and the characteristic absorption peaks of wood are almost the same, including 3345 cm -1 (O-H stretch), 1733 cm -1 (C O stretch, molecular motion of hemicellulose), 1,593 cm -1 and 1,505 cm -1 (aromatic skeleton vibration, molecular movement of lignin), 1,235 cm -1 (C-O stretch), 1,034 cm -1 (C-H stretch) and other absorption peaks, which indicate the chemical structure of the CW wood has not been damaged (Wu et al, 2020a;Yang et al, 2021). At the same time, the FTIR of CW also showed the characteristic absorption peaks of 2,915 cm -1 and 2,850 cm -1 (C-H stretch), 1,465 cm -1 (CH 2 bend) and 815 cm -1 (C-H bend) representing alkanes, which is mainly caused by the hexadecyltrimethoxysilane component in the coating.…”