All lignin, all green composites
The importance of reducing CO2 emissions and consequently decreasing the extent of global warming necessitate the development of green chemistry techniques to replace petrochemical-based polymers with renewables and to enable carbon sequestration in value-added materials to reach negative emissions. Lignin, as the second largest source of natural polymers after cellulose and the largest source of bio-aromatics, is a potential candidate for new bio-based materials. The challenge is to overcome the inferior mechanical properties of lignin and to understand the underlying reasons. A substantial amount of the work done so far has focused on chemical modification of lignin to make it suitable in polymer blends and composites. Lignin has also been studied as a replacement for phenol in phenol-formaldehyde resins to arrive at renewable thermosets. The objective of the present work is to combine the covalent and non-covalent approaches to develop new routes for using lignin as reinforcement in all-lignin composites. We study how the structure and morphology of lignin affect the mechanical properties and morphology from the nanoscale to the macroscopic length scale of the composites. In addition to delivering this fundamental information of composites, we intend to pave the way to the development of processing techniques to build hierarchical structures from lignin and to provide a greener path to engineered materials. Overall, the project presents new ways to utilize C1 chemicals derived from atmospheric CO2 to develop an all lignin, all green product.