Molecular Dynamics Simulations of Cellulose Interaction With Polymeric Solid Acid

A novel polymeric solid acid catalyst has been designed for cellulose depolymerization. A poly (styrene sulfonic acid) (PSSA) polymer chain is immobilized on substrate surface and used to catalyze biomass hydrolysis. A neighboring poly (vinyl imidazolium chloride) ionic liquid (PIL) polymer chain is grafted from the surface to help solubilize lignocellulosic biomass and enhance the catalytic activity. Over 97% and 32% total reducing sugar (TRS) yields were obtained for cellulose hydrolysis in [EMIM]Cl and water solutions respectively. The catalytic activity for cellulose hydrolysis is found to depend strongly on the chain length and chain density of the two polymeric nanostructures. Further, the interactions between the cellulose and the polymer chains also play a critical role in the conversion rate. Here classical molecular dynamics simulations were conducted to investigate the interactions between the PSSA and PIL polymer chains and the cellulose substrate in both aqueous solution and ionic liquid solvent. The effects of copolymerization and ring substitution on the polymer chains were determined.