Top-down fabrication of wood hydrogels: From preparation to application.

[Display omitted] • Research progress in the preparation of wood hydrogels by the top-down method is reviewed. • The advantages of wood hydrogels in structure and property are highlighted. • The relationship between wood hydrogel preparation-properties-applications is elucidated. • The challenges and outlooks for the future development are presented. Wood-based materials have attracted increasing interests due to the progress of wood nanotechnology. In such cases, wood hydrogels fabricated by a top-down approach demonstrate huge potential in smart electronics, sensors, biomedical and energy harvesting/storage devices. Distinct from cellulose or lignin hydrogels prepared from bottom-up technology, wood hydrogels retain the hierarchical/anisotropic structure of natural wood. In addition, wood hydrogels can be produced in a facile, scalable and energy-saving way. In this short review, a brief overview of the recent development of wood hydrogels is provided, with special emphasis on the preparation methods and structural characteristics. The various applications of wood hydrogels are then discussed from a preparation-performance-application point of view. This is followed by a summary of the challenges and perspective for the future improvement of wood hydrogels, as well as guidance for the development of green scalable wood-based functional polymeric materials. [ABSTRACT FROM AUTHOR]