Deep Eutectic Solvent-Extracted Lignin in Organic and Aqueous Solvents

Lignin is a phenolic biopolymer, which is found in most vascular plants. Lignin valorization to value-added chemicals, including as plastics additives and formulation components are creating new opportunities as a sustainable replacement for petrochemically derived materials. Extraction with deep eutectic solvents can functionalise the lignin during extraction, resulting in lignins with altered polarity and solubility in common processing solvents. Aggregation of lignin in solution affects its incorporation into formulations and composites as well as altering apparent molecular weight distributions in GPC. In this study we will use SANS to study lignins derived by extraction from different biomass sources using a choline chloride:p-toluene sulfonic acid:glycerol solvent which functionalises the lignin with the glycerol, dependant on extraction conditions. We will use deuterated solvents to give sufficient contrast with the h-lignin to obtain information on the aggregation state and polymer solution conformation. This data will enable us to compare the polymeric lignin conformations in solution as concentration and temperature is varied, for comparison with GPC and NMR data and to improve processability into coatings and composites.