Molecular dynamics simulation of functionalized nanofibrillar cellulose

An atomistic model of carboxylated nanocellulose fibril is formed and simulated using all-atom molecular dynamics. The major research is on a modification method, TEMPO-catalyzed oxidation, which introduces specific carboxyl functional groups on the surface of nanocellulose structures using MD simulation. Extent of functionalization for COO-NA has been done with respect to number of functional groups available after oxidation reaction. Energy minimization at constant pressure and temperature for longer time scales gives more relaxed fibril structure. The structure of the fibril undergoes significant twisting related to reorganization of the chains within its structure. The radial mean square distance analysis indicates total convergence of the structure towards an equilibrium state. Similarly, radial distribution of functionalized groups with respect to time represents sound and stable attachment of the groups to fibril chains. This structure can be used for the further molecular dynamic studies.