(657h) Novel Viscoelastic Material Consisted of Polymeric Lignin

Lignin, a renewable resource available from lignocellulosic biomass, has the potential to replace petrochemical feedstock in the production of aromatic polymers. Applications of lignin as a polymer material, however, is hindered by brittleness and thermal instability of the material. Unless blended with other polymers (e.g. PLA, PP, PVA, PET) or added as a filler in composites, technical lignins are not suited for material applications. The complexity in lignin structure and depolymerization chemistry also complicates the use of lignin as a source of polymer building blocks.

We present a new process that converts enzymatic lignin to a viscoelastic material that contains over 80% lignin by weight. In this process, lignin is oxidatively functionalized and repolymerized using renewable chemicals (hydrogen peroxide, methanol, and DMSO) under mild conditions (ambient pressure, under 100 degrees C), yielding a homogeneous polymeric material. The synthesized material contains native beta-aryl ether linkages in lignin, while also exhibiting new viscoelastic properties distinct from the starting material. Rheological analyses of this new material has demonstrated stress response characteristics that have never been reported on lignin-rich materials. In an effort to enhance the viscoelasticity of the lignin-rich material, our studies on lignin functionalization chemistry revealed the association between polymerization parameters and mechanical properties.