Recent Advances in Thermoset and Thermoplastic Polymeric Materials Produced using Technical and Depolymerized Native Lignins

Lignin is an important renewable aromatic biopolymer that will have a significant role to play in the future of sustainable bio-based polymers. Replacing petrochemical feedstocks with lignin-based monomers/macromolecules will lead to the deployment of new thermoset and thermoplastic materials with unique functionality and performance, and lower carbon footprints. This chapter describes recent advances in lignin-based thermoset and thermoplastic polymers developed using technical lignins and depolymerized native lignins. Technical lignins, obtained from traditional pulping of lignocellulosic biomass, have a long history of use in the research and development of bio-based polymers and materials. More recently, reductive catalytic fractionation processes that depolymerize native lignins in biomass have emerged as alternative pathways to producing lignin-based chemical feedstocks for new polymeric materials. For thermoset polymers, this chapter focuses on the interesting, recent progress made on lignin-based polyurethanes, epoxy resins, and phenol-formaldehyde resins. In the thermoplastics area, this chapter emphasizes the developments in two important graft polymerization methods using lignin, namely, ring-opening polymerization using renewable cyclic esters and controlled radical polymerization using vinylic monomers. In addition, recent developments in lignin-based thermoplastic polyurethanes using technical and depolymerized native lignins are discussed. The chapter concludes with author perspectives on the future of lignin-based thermosets and thermoplastic polymeric materials.