Sub-micro and nano-lignin materials: Small size and rapid progress

Abstract Lignin is the second most abundant biopolymer and the main source of aromatic structures on the earth. As a by-product of cellulose in the paper pulp production, lignin has rather low added-value applications. Sub-micro and nano- lignin materials maybe open promising high added-value applications. These new fields have brought about renewed interest for lignin. In this paper, the current developments of sub-micro and nano-lignin materials were reviewed. The synthetic routes between sub-micro and nano- lignin materials were summarized. All the different shapes, microstructures, and properties of these sub-micro and nano- lignin materials were compared with that of conventional lignin. The future trend toward micro- and nanostructured lignin-based materials is also suggested. It is expected that the small size of sub-micro and nano-lignin materials displays great progress, which are promising applications of various fields in the near future.