Existing lignocellulosic biomass fractionation processes produce lignin with random, interunit C–C bonds that inhibit its depolymerization and constrain its use. Here, we exploit the aldehyde stabilization of lignin to tailor its structure, functionality, and resulting properties, expanding its potential uses. We use one or two bifunctional aldehydes to install controlled quantities of specific functionalities on lignin and thereby control its physical properties and reactivity. Rational selection of the aldehyde allows for the formation of acetal-stabilised lignins that are soluble in either polar or non-polar solvents such as water and toluene. Exploiting these novel solubility properties, we can exploit solvent effects in lignin hydrogenolysis to tune the product distributions of this reaction. Similalry, aldehyde selection can allow us to instally reactive functional groups such as carboxylic acids or aldehydes on the lignin backbone for use in subsequent transformation such as phenolation or crosslinking with gelatin. Notably, we show that only lignin functionalized with both carboxylate and aldehyde groups successfully crosslinked with the gelatin allowing us to tune the final hydrogel's properties. Overall, we demonstrate that multifunctional lignins can be designed according to their final application and extracted in a single step from lignocellulosic biomass. Their controlled properties allows for the possibility to integrate these lignins into tailored upgrading pathways or into novel materials for high-end applications.

Expanding lignin properties and its potential applications through controlled functionalization

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.