Lignin Exploitation and Valorization: Chemicals, Building blocks, and Polymers

Lignin is the second most abundant natural renewable polymer after cellulose, currently being produced in large quantities through chemical pulping and cellulosic ethanol production processes. Although currently, from the agroindustrial point of view, it is considered a recalcitrant byproduct that can be only valorized by combustion in the generation of power for pulping plants, the proper valorization of its unique chemical structure is of paramount importance for the success of several agroforestry biorefineries and thus the recipient of great interest for the scientific and industrial community. Many studies have been conducted on lignin utilization. The presence of various functional groups, its biodegradability, and its antioxidant character make it a potential candidate for the production of bio-aromatic chemicals (e.g., vanillin, phenols, and antioxidants), building blocks (monomers), and bio-based polymeric materials (e.g., resins and polymers). Additionally, lignin is the source of biobased carbon fibers in new-generation biocomposites.

This Research Topic aims to cover recent progress and trends in the valorization of lignin as a key recalcitrant byproduct in several agroforestry biorefineries and it will target three main themes. Special attention will be devoted to original studies focused on lignin’s controlled degradation to obtain chemicals for high-value applications, as well as lignin refining to achieve reproducible lignin fractions. A second theme will focus on the chemical modification of lignin and its derivates to fabricate building blocks suitable for material science (monomers, additives, antioxidants, reinforcing agents). A final theme will refer to the fabrication of lignin-based thermoplastic and thermosetting biocomposites, and the contribution of lignin structure to the material’s performance.

We welcome submissions of different types of manuscripts: Original Research, Reviews and Mini Reviews including but not limited to:

• New valorization methods of lignin from agroforestry biorefineries;
• Chemical modification/depolymerization of lignin;
• Fractionation/purification of lignin;
• Production of bio-aromatic chemicals from lignin (e.g., vanillin, phenols);
• Synthesis of lignin-based additives for polymers ( e.g., plasticizers, antioxidants, flame retardant additives);
• Production of lignin-deriving monomers and building blocks;
• Pyrolysis or hydrothermal liquefaction of lignin for bio-oils production;
• Synthesis of bio-based polymeric materials from lignin (e.g., resins and polymers);
• Biocomposites based on lignin;
• Production of carbon fibers as reinforcement fillers in thermoplastic polymers or lightweight composite materials.

Keywords: Lignin, Agroforestry, Biorefinery, Depolymerization, Bio-aromatic chemicals, Fractionation and purification, Phenols, Monomers, Resins, Polymers, Biocomposites

Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.