(534g) Chemical Breakdown and Reinforcement of Lignocellulosic Cell Walls

The development of novel functional materials from renewable sources has become an important area of focus in the realm of material science. Naturally occurring polymers, such as cellulose, can be readily obtained from the biosphere. Lignocellulosic materials constitute one of the largest classes of biomass, presenting a widely available resource for functional materials often considered as waste. The inherent 3D hierarchical structure of lignocellulose provides excellent mechanical properties at low density, while the individual chemical constituents (cellulose, hemicellulose, lignin) carry significant promise in the production or refinement of biofuels. In this study, cell wall specific reinforcement was accomplished through mineralization of balsa wood (Ochroma pyramidale) with nanoscale ferrihydrite (Fh) and characterized using a variety of imaging methods and multiscale mechanical testing, including Micro-computed X-Ray Tomography (MicroCT), Raman Spectroscopy, and Energy Dispersive X-Ray Spectroscopy (SEM-EDS). Changes in the mechanical properties of the chemically altered cell wall were assessed using in-situ SEM-Nanoindentation and Advanced Atomic Force Microscopy (AFM). We observed a significant increase in hardness and stiffness in the S2 cell wall of ferrihydrite-reinforced wood compared with pristine wood. To study the selective removal of lignin or cellulose from the wood cell wall, chemically (H₂O₂/CH₃OOH) and enzymatically (cellulase) treated samples were thoroughly characterized by NanoIR and Band Excitation AFM (BE-AFM). This analysis allowed us to correlate the resulting chemical degradation to changes in observed mechanics. Preliminary BE-AFM results suggest a complete degradation of parts of the delignified S2 cell wall while the enzymatic treatment appears to degrade the cell wall through fission lines between lumen and middle lamella.