AN ATOMIC MODEL OF CELLULOSE NETWORK IN WOOD CELL WALL

Wood is composed of parallel columns of long hollow cells which are made up of layered composite of semi-crystalline cellulose fibrils embedded in an amorphous matrix of hemicellulose and lignin. The extraordinary mechanical performance of wood is believed to result from a molecular mechanism operated through hydrogen bond connection. However, the molecular interactions, the assembly method of cell-wall components, as well as the molecular mechanisms responsible for the deformation of wood, are not well understood yet. Progress in studying the superior mechanical properties of wood cell is severely hindered because of this fact. To overcome this barrier, the foremost step is to build up an atomic model of the native cellulose fibril network, which is the dominant polysaccharide in wood cell walls. Then, in this work, we proposed the atomic models to study the cellulose network which includes a single cellulose microfibril (MF), and a thin film which is built up by first secondary layers (S1) and second secondary layers (S2) composed of cellulose MF with periodic boundary conditions. Additionally, we investigated the length effect of the Microfibril and compared the effect of explicit water solvent environment with the vacuum environment. Moreover, the spatial arrangements of these atomic models have been determined by molecular mechanics simulation (energy minimization). The hydrogen bond length of the crystalline part of the inner cellulose was evaluated using first principle calculation.