Coarse-Grained Model for the Interconversion between Native and Liquid Ammonia-Treated Crystalline Cellulose

We present the results of Langevin dynamics simulations on a coarse–grained model for a structural transition in crystalline cellulose pertinent to the cellulose degradation problem. We analyze two different cellulose crystalline forms: cellulose Iβ (the natural form of cellulose) and cellulose IIII (obtained after cellulose Iβ is treated with anhydrous liquid ammonia). Cellulose IIII has been the focus of wide interest in the field of cellulosic biofuels, as it can be efficiently hydrolyzed to readily fermentable glucose (its enzymatic degradation rates are up to 5-fold higher than those of cellulose Iβ). The coarse-grained model presented in this study is based on a simplified geometry and on an effective potential mimicking the changes in both intracrystalline hydrogen bonds and stacking interactions during the transition from cellulose Iβ to cellulose IIII. The model reproduces both structural and thermomechanical properties of cellulose Iβ and IIII. The work presented herein describes the structural ...