The work, led by Amit Naskar, used acetonitrile to extract lignin with carboxylic acid functional groups, then used polyethylene glycol to generate covalent and hydrogen bonds within the material.
“This network contains both stiff phases, from the lignin, and soft phases, from the PEG,” Naskar tells ChemEngOnline. “The resulting material is highly elastic, with the ability to stretch by over 2,000%, as well as very tough.” The large amount of hydrogen bonds also means that the material can self-heal.
The team is now looking at ways the material could be used in coatings, glues, and hydrogels. Lignin makes up 25-35% of woody biomass but is considered a waste material of biofuels production and paper industries.