Recent Advances in Hydrophobic Modification of Nanocellulose

As a kind of renewable nanomaterial, nanocellulose displays excellent performances and exhibits wide application potentials. In general, nanocellulose has strong hydrophilicity due to the presence of abundant hydroxyl groups or the hydrophilic functional groups introduced during the preparation process. Although these hydrophilic groups benefit the nanocellulose with great application potential that is used in aqueous media (e.g., rheology modifier, hydrogels), they do hinder the performance of nanocellulose used as reinforcing agents for hydrophobic polymers and reduce the stability of the self-assembled nanostructure (e.g., nanopaper, aerogel) in a high-humidity environment. Thus, this review aims to summarize recent advances in the hydrophobic modification of nanocellulose, mainly in three aspects: physical adsorption, surface chemical modification (e.g., silylation, alkanoylation, esterification), and polymer graft copolymerization. In addition, the current limitations and future prospects of hydrophobic modification of nanocellulose are proposed.