Speaker
Description
Progress in understanding the molecular architecture of wood secondary cell walls has enabled the use of computational methods, and molecular simulation in particular, to investigate their nanostructure and water interactions. We report simulation studies that address the structure of wood cell walls, and cellulosic materials derived from them, at different length scales and levels of approximation. We develop molecular models of cellulose microfibrils both as individual nano-objects and in aggregated states mimicking their cell wall environment, considering also their interactions with hemicelluloses, lignin and water. We carry out simulations of their response to drying and compare the predictions, among others, to X-ray and neutron scattering experiments on Norway spruce wood samples. The models reproduce detailed features of the experimental data, thus supporting the underlying structural hypotheses. Our findings provide insight into the structure and stability of microfibril interfaces, their role in stress transfer and in controlling water diffusivity. We further develop stochastic three-phase models of aligned microfibril structures in the sub-100 nm length scale, and use them as a basis for a scattering analysis tool for wood samples. Besides contributing to the understanding of wood cell wall nanostructure, our research addresses phenomena that are relevant for many of the current processing routes and uses of cellulosic raw materials.