Navigating the Forest of Lignin-Derived Monomers for Polymer Synthesis

The field of lignin-based polymeric materials is undergoing rapid development, driven by increasing sustainability demands. However, progress in lignin-derived materials is often pursued from different disciplinary perspectives─biomass chemistry, organic synthesis, and polymer materials science─using field-specific metrics, resulting in fragmented knowledge. This Perspective examines the lignin-to-materials pathway by connecting advances in the conversion of lignin into platform molecules, their transformation into monomers, and the synthesis of polymeric materials through representative examples. We perform rough estimates of sustainably available lignin streams and compare them with current polymer production, indicating that lignin could potentially supply aromatic monomers at scales comparable to existing markets. Through analysis of key literature on lignin-to-monomers and monomers-to-polymer strategies, we identify critical directions for lignin-to-materials development. These include refinery concepts that utilize complex lignin-derived substrates as primary building blocks, prioritizing the use of their inherent functionality before stepwise defunctionalization, and adopting application-driven materials design, in which the requirements of a target application guide monomer and polymer selection rather than attempting to reproduce the molecular structures of the petroleum-derived polymers currently used for those applications.