Development of a New Coarse-Grained Model to Simulate Assembly of Cellulose Chains Due to Hydrogen Bonding.

In this work, we present a new coarse-grained (CG) model that captures the directional hydrogen bonding interactions that drive cellulose chains to assemble into ordered aggregates. This CG model balances the incorporation of chemical details at the monomer level needed to represent directional interactions and the coarse-graining needed to capture large length scales and time scales associated with macromolecular assembly. We validate this CG model by first comparing the cellulose single-chain structure in the CG molecular dynamics (MD) simulations with that in atomistic MD simulations. We also compare the hydrogen bonding pattern, interchain distance, and interchain orientation seen in assembled cellulose chains observed in CG MD simulations with those seen in experimental crystal structures of cellulose. Upon validation, we present the aggregation behavior of cellulose chains with "silenced" hydrogen bonding site interactions to mimic cellulose chains that are chemically modified at the donor and acceptor hydrogen bonding sites (e.g., methylcellulose). We expect this type of CG model to be useful in predicting the morphology of cellulose chains in solution under a wide range of solution conditions and chemical modifications.