Intersecting Polymer Chemistry with Sustainability in Lignin-Derivable Macromolecular Systems

The valorization of lignin-derivable (LD) small molecules to polymeric materials offers a promising avenue to reduce dependences on petrochemical feedstocks in material design. However, challenges in achieving semicrystallinity and material circularity of chain-growth, LD macromolecules have limited the practical application of lignin-based polymers. Here, we describe strategies to address these targets through considerations in LD monomer design. First, we demonstrate the development of LD vinyl monomers that can undergo living polymerizations to yield stereoregular, semicrystalline macromolecules. Tailored monomer design enabled polymerization under mild synthesis conditions and gave rise to desirable crystallinities and thermal properties in the resulting macromolecules. Then, we detail the development of advanced recycling methods to thermally deconstruct high-glass-transition temperature (> 100 °C) LD polymethacrylates to their constituent monomers in high yields and purities. Understandings of the thermodynamics and kinetics underlying depolymerization enabled bulk chemical recycling to monomers that were then upcycled to value-added polymers. The discoveries described herein offer pathways to broaden the application potential of LD macromolecules and design circular LD polymeric materials.