New Soft Materials from Lignin
Today, carbon-based (soft) materials are derived primarily from petrochemical platforms (e.g. ethylene, propylene, BTX, etc.). When biomass is considered as a platform for new materials, there is a temptation to simply break biomass down into known platform molecules and then build those back up into new materials. Our research is predicated on the idea that there are undiscovered routes to valorize biomass and fractions directly to new, so-called “bio-advantaged” materials. We are interested in exploring these Frontiers in Biorefining.
One avenue we have explored is the incorporation of lignin as a macromolecular crosslinking agent in hydrogels. We have shown that the hydrophobic structure of lignin can be modified to lend itself to incorporation into the chemical structure of hydrogels. We have shown that these hydrogels have enhanced water retention when compared to the lignin-free materials. We are exploring these materials in advanced agricultural products that require long-term water retention, such as seed coatings that enhance germination.
See our manuscript in Biomacromolecules for more info.
We are also investigating lignin as a structural oligomer in multi-component photoactive resins. These materials are liquids that harden with light exposure, and have multiple applications as coatings and adhesives. We have shown that lignin imparts interesting material properties to cured polymers, and we are investigating chemical modifications of lignin so that it can function as several (or all) of the components in these engineered resins.
One exciting application of these lignin-containing resins is to 3D printing by stereolithography (SLA). SLA is a form of 3D printing that uses a laser to build up solid objects from a liquid bath. High resolution and print speed are hallmarks of SLA, and our research has shown that the addition of lignin to SLA resins increases the kinetics of photopolymerization (and hence the printing speed). Moreover, we have shown that careful modifications of lignin actually allow large amounts of lignin (we hypothesize up to 60%) to be added to the resins with no loss of printing resolution or speed.