The application of nanocellulose in eco-friendly lubricants: A review

Lubricants are widely employed in mechanical systems to reduce energy loss and the wear induced by friction. With increasing concern for environmental protection, the development of eco-friendly lubricants has become increasingly significant. Nanocellulose, a natural material derived from cellulose, has attracted increasing research attention in the field of lubrication due to its renewable, nontoxic, and biodegradable properties. Focusing on this emerging research topic, this state-of-the-art review first analyzes the theoretical basis of applying nanocellulose as a thickening agent in eco-friendly lubricating formulations. Subsequently, it presents an overview of research advances in cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), categorized by their applications as additives or thickeners in aqueous, oil, and grease lubricants. Moreover, this review also highlights the challenges associated with eco-friendly lubricants based on nanocellulose and offers suggestions for future investigations in this field. It is hoped that this review will guide the research direction of eco-friendly lubricants and promote the development of nanocellulose materials for industrial lubrication applications.