Breaking down cellulose fibrils with a mid-infrared laser

Abstract: A novel process for the separation of crystalline cellulose in water into single polysaccharide strands is proposed that does not require high temperatures or other chemical reactants. We have modeled the behavior of a 36-strand cellulose I β crystalline bundle when subjected to picosecond mid-infrared laser pulses using all-atom non-equilibrium molecular dynamics simulations. We show that mid-infrared laser pulses that induce resonance deformations in the C–O–H angles of the hydroxyl groups that are involved in the hydrogen bonding network of cellulose, rapidly cause the cellulose bundles to dissociate into single strands solvated by the water. The laser pulses selectively disrupt intra- and inter-chain hydrogen bonds that maintain the polysaccharide strands in sheets and bundles, causing cellulose to dissolve into single strands whose end-to-end lengths remain similar to those in the original cellulose crystalline bundle. This proof-of-concept work provides guidance for experiments that may provide insight into the mechanism of cellulase enzymes whose improvement could lead to increased production of ethanol from cellulose, and possibly spur the development of new nanomaterial engineering techniques. Graphical Abstract: [Figure not available: see fulltext.]