Calculations of Young's Moduli for Cellulose Iβ

In this presentation, we will discuss a series of Young’s modulus determinations that relied on molecular mechanics (MM3) and quantum mechanics (QM) calculations with models of cellulose I_β. Preliminary determinations were presented at the 2010 Beltwide Cotton Conferences: “Preliminary modulus calculations for cellulose I”. However, revised results and several new findings will be presented. We will discuss our computations that used the second generation empirical force field MM3 with a disaccharide cellulose model, 1,4'-O-dimethyl-β-cellobioside (DMCB), and an analogue, 2,3,6,2',3',6'-hexadeoxy-1,4'-O-dimethyl-β-cellobioside (DODMCB), that cannot make hydrogen bonds. These computations revealed a considerable contribution of intramolecular hydrogen bonding to the molecular stiffness of cellulose I_β. We will also discuss MM calculations with extended cellulose chains (10-40 glucose units). These calculations resulted in modulus values, 126.0-146.7 GPa, comparable to reported modulus values for cellulose I_β.