Polymeric composites and nanocomposites containing lignin: structure and applications

The growing interest to develop green and biobased products promoted the investigation and the use of lignin-based systems. Several factors have been found to affect the active properties (UV-absorption, antimicrobial, antifungal, and antioxidant properties) of lignin: the origin of the extracted lignin, shape, particle size, charge, surface chemistry, and the type of tested microorganisms. Lignin at micro and nanodimensions is considered a strategic additive to be used in several specific sectors. The characteristic of lignins allows the application of this natural and green active ingredient in food and feedstuff, commodity products with antimicrobial or antioxidant activities, and UV absorption. This chapter aims to summarize the main applications of lignin at the microscale and nanoscale when dispersed in different polymeric matrices. The main roles of lignin-based materials considered in this chapter are oriented to the study and analysis of UV absorption, antimicrobial, antioxidant, antiinflammatory, antiviral, and antimutagenic properties. The overall performance of different systems will be briefly revised, stressing and highlighting the role of lignin in different application sectors, such as UV absorption, food, drug delivery, medical, plant protection, environmental remediation, photocatalysis, and photovoltaics sectors.