Understanding the Interactions of N-Methylmorpholine N-Oxide with Cellulose

The abundance and energy content of native cellulose makes it an extremely important raw material and source for sustainable biofuels. A major challenge in processing natural cellulose lies in its strong resistance to dissolution. Only a limited number of conventional solvents have been found to effectively dissolve cellulose and the mechanisms of action still remains unclear. We study the dissolution of cellulose in N-methylmorpholine N-oxide (NMMO) hydrate, the key solvent of one of the most successful commercial processes for dissolving cellulose, via molecular simulation. The solubility of cellulose is highly sensitive to the concentration of water and we examine the behavior of these solutions over the full concentration range. We calculate the thermodynamic driving forces leading to dissolution, the disruption of the hydrogen bonding network, the role that water plays in this process and the underlying molecular interactions that make these solvents effective in dissolving cellulose. Finally, we discuss what can be learned from understanding of NMMO that can be applied to the search for more better, cheaper and more environmentally-friendly alternatives.