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.

Methods for determining a source of wood products, wood products, wood preservative compositions, and methods of treating wood substrates are provided. The method comprises detecting a presence of a marker in the wood product and determining the source of the wood product based on the detected presence of the marker.

Methods for determining a source of wood products, wood products, wood preservative compositions, and methods of treating wood substrates are provided. The method comprises detecting a presence of a marker in the wood product and determining the source of the wood product based on the detected presence of the marker.

A method for preparing a wood preservative composition, includes modifying lignin with Na.sub.2B.sub.4O.sub.7 or NaNO.sub.3 and then with a chromium (II) salt, copper (II), cadmium (II) or zinc (II), for example, metal nitrates (Cr(NO.sub.3).sub.2, Cu(NO.sub.3).sub.2, Cd(NO.sub.3).sub.2, Zn(NO.sub.3).sub.2); to the preservative obtainable by this method; and to a method for preserving wood; and to the preserved wood. The preservative prevents degradation by xylophagous and fungal agents, and also improves some properties of the wood, and the hygroscopicity and fire resistance.

A method for preparing a wood preservative composition, includes modifying lignin with Na.sub.2B.sub.4O.sub.7 or NaNO.sub.3 and then with a chromium (II) salt, copper (II), cadmium (II) or zinc (II), for example, metal nitrates (Cr(NO.sub.3).sub.2, Cu(NO.sub.3).sub.2, Cd(NO.sub.3).sub.2, Zn(NO.sub.3).sub.2); to the preservative obtainable by this method; and to a method for preserving wood; and to the preserved wood. The preservative prevents degradation by xylophagous and fungal agents, and also improves some properties of the wood, and the hygroscopicity and fire resistance.

A crosslinking polyvinyl acetate (XPVAc or X-PVAc) adhesive is applied as a primer (i.e., a basecoat) or an exterior coat (i.e., a top coat) on a wood preservation product which is mainly treated with a water-based preservative. By sealing the exterior wood surfaces, the new coating system not only effectively prevents the leaching of the preservative by bonding and chelating with the unfixed preservative compounds or complexes at the surface layer, but it also significantly reduces surface aging of wood, maintains effective preservation functions, and provides a longer service life to the wood preservation product.