(83b) Molecular Origin of Cellulose Dissolution in Novel Solvent Mixtures

Biomass contains abundant amounts of
cellulose as crystalline microfibrils. A limiting
step to using cellulose as an alternative energy source, however, is the
hydrolysis of the biomass and subsequent transformation into fuels. Cellulose
is insoluble in most solvents including organic solvents and water, but it is
soluble in some ionic liquids like BMIM-Cl. This project aims to find
alternative solvents that are less expensive and are more environmentally
benign than the ionic liquids.

Figures: (Above)
Setup of glucan chains in randomized solvent mixture.
Orange-pyridine, Blue- propanol, Multicolor- glucan chains. (Graph Below) Contacts
after equilibration in a Pyridine-Propanol solvent mixture. (Table
Below) Contacts after equilibration in a pure solvents.

All-atom molecular
dynamics simulations were performed on dissociated glucan
chains separated by multiple (4-5) solvation shells, in the presence of several
novel solvents and solvent mixtures. The solubility of the chains in each
solvent was indicated by contacts calculations after the equilibration of the
molecular dynamics. It was discovered that pyridine and imidazole acted as the
best solvents because their aromatic electronic structure was able to
effectively disrupt the inter-sheet interactions among the glucan
chains in the axial direction, and because perturbation of the solvent
interactions in the presence of glucan chains was
minimal.