Mechanically Tunable and Reconstructable Lignin Thermosets via “Click” Chemistry and Surface Functionalization

Among the most abundant biomass, lignin is an appealing yet challenging feedstock for manufacturing sustainable materials. The polyphenolic structure and globular architecture of lignin makes it a mechanically weak material for being incorporated in polymer composites. Upon surface modification with functionalized silyl ether groups via thiol-ene chemistry in this work, lignin was cross-linked to create reconstructable thermosets. These thermosets exhibit not only enhanced mechanical properties but also improved degradability. The synthesis of different cross-linkers was used to explore the structure–property relationship. Altering the cross-linking density and the size of cross-linkers has a large impact on the mechanical properties of the final thermosets. Furthermore, the chemical recycling of these thermosets was explored for the conversion to initial motifs under basic environments.