A mini-review on polyvinyl alcohol/lignin (nano)composites: Preparation, applications and perspectives

As a water soluble polymer, polyvinyl alcohol (PVA) has gained popularity due to its excellent chemical stability, biodegradability and biocompatibility, as well as film-forming and gas barrier properties. Lignin is the most abundant bio-based polyphenol material, which has been widely used in agriculture, biomedicine, food packaging, cosmetics and intelligent materials due to its remarkable biocompatibility, biodegradability and renewability, as well as antibacterial, antioxidative and UV resistant properties. Meanwhile, due to the small size effect, the nano-sized lignin has more significant mechanical characteristics and biological activity enhancement effects than macro-sized lignin. Using lignin to produce high value-added products could not only make full use of renewable resources including biomass, but also promote the effective development of green resources. This mini-review focuses on the most recent research progress of PVA/lignin (nano)composites used as high mechanical strength, antibacterial, antioxidative, anti-UV, electrode, flame retardant, dye adsorption, flexible sensor materials and so on. By taking some typical examples, the preparation methods, properties and their potential applications of these composites will be described. Finally, the future development and Life Cycle Assessment of the lignin-based composites are proposed, such as lower cost and higher yield for the nanolignin preparation, more environmentally friendly methods for modification, and the potential commercialization of PVA/lignin composite products.