University System of Maryland

Jianwei Song

Liangbing Hu

Mingwei Zhu

Chaoji Chen

Amy Gong

Tian Li

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

Strong and tough structural wood materials, and methods for fabricating and use thereof

Highly transparent (up to 92% light transmittance) wood composites have been developed. The process of fabricating the transparent wood composites includes lignin removal followed by index-matching polymer infiltration resulted in fabrication of the transparent wood composites with preserved naturally aligned nanoscale fibers. The thickness of the transparent wood composite can be tailored by controlling the thickness of the initial wood substrate. The optical transmittance can be tailored by selecting infiltrating polymers with different refractive indices. The transparent wood composites have a range of applications in biodegradable electronics, optoelectronics, as well as structural and energy efficient building materials. By coating the transparent wood composite layer on the surface of GaAs thin film solar cell, an 18% enhancement in the overall energy conversion efficiency has been attained.

Transparent wood composite, systems and method of fabrication

A flexible structure is formed by subjecting cellulose-based natural wood material to a chemical treatment that partially removes hemicellulose and lignin therefrom. The treated wood has a unique 3-D porous structure with numerous channels, excellent biodegradability and biocompatibility, and improved flexibility as compared to the natural wood. By further modifying the treated wood, the structure can be adapted to particular applications. For example, nanoparticles, nanowires, carbon nanotubes, or any other coating or material can be added to the treated wood to form a hybrid structure. In some embodiments, open lumina within the structure can be at least partially filled with a non-wood substance, such as a flexible polymer, or with entangled cellulose nanofibers. The unique architecture and superior properties of the flexible wood allow for its use in various applications, such as, but not limited to, structural materials, solar thermal devices, flexible electronics, tissue engineering, thermal management, and energy storage.

Flexible wood structures and devices, and methods for fabricating and use thereof

A delignified wood material is formed by removing substantially all of the lignin from natural wood. The resulting delignified wood retains cellulose-based lumina of the natural wood, with nanofibers of the cellulose microfibrils being substantially aligned along a common direction. The unique microstructure and composition of the delignified wood can provide advantageous thermal insulation and mechanical properties, among other advantages described herein. The thermal and mechanical properties of the delignified wood material can be tailored by pressing or densifying the delignified wood, with increased densification yielding improved strength and thermal conductivity. The chemical composition of the delignified wood also offers unique optical properties that enable passive cooling under solar illumination.

Growing community of inventors

College Park, MD, United States of America

Jianwei Song