(253e) Fractionation and Chemical Modification of Celf Lignin: Toward Production of Next-Generation of Polyurethane

The effective valorization of lignin to renewable polymers such as polyurethanes (PU) is a promising pathway for producing renewable plastics, provided that the process can be realized cost-effectively using environmentally sustainable methods (e.g., isocyanate free). A prerequisite of utilizing lignin in such area is to develop efficient lignin fractionation and modification strategies that can decrease the lignin heterogeneity and tune the chemical structure of lignin streams. For this purpose, several common organic solvents were screened for their ability to fractionate the Co-Solvent Enhanced Lignocellulosic Fractionation (CELF) lignin. A solvent extraction sequence is then proposed to obtain CELF lignin fractions with different chemical functionalities and molecular weights. The obtained CELF lignin fractions were subsequently modified by epoxidation followed by CO₂ cycloaddition to produce carbonated CELF lignin. A green and non-toxic CELF lignin-based non-isocyanate polyurethanes (NIPUs) were finally synthesized via the polyaddition between the tailored carbonated CELF lignin and commercially available diamines. The final NIPU products obtained using this synthetic route were analyzed for their morphological, structural, and thermal properties, and the relationship between lignin structures and NIPU properties was established.