Sorption investigated with MD
Wood cell wall composite material is made of the stiff cellulose microfibrils embedded in a soft polymeric matrix. The microfibrils are made of crystalline cellulose? bound by hydrophilic amorphous hemicellulose, thus making long thin filaments. In between the microfibrils, the hydrophilic amorphous matrix is composed of different hemicelluloses and of two states of lignin.
Water molecules can easily form hydrogen bonds with the hydroxyl groups of the amorphous components. Thus, as the adsorption process involves mainly atomistic interactions, molecular dynamics (MD) simulations are an appropriate tool for its investigation. Typical scales of the process range from angstroms to micrometers.
With MD, the explicit movement of water molecules and polymeric chains is determined. Systems have a few nanometers and are put in full periodic boundary conditions, for 10 ns. The wood cell wall S2 layer is studied at the nanoscale with special emphasis on its interaction with water molecules.
Sorption is often accompanied by deformation of the material. This interaction is studied on membranes with a parallel arrangement of tubular pores and on amorphous polymer.
Publications
Kulasinski K, Guyer R, Derome D, et al. Water Diffusion in Amorphous Hydrophilic Systems: A Stop and Go Process. Langmuir, 2015, 31(39): 10843-10849.
Kulasinski K, Guyer R, Derome D, et al. Poroelastic model for adsorption-induced deformation of biopolymers obtained from molecular simulations. Physical Review E, 2015, 92(2): 022605.
Kulasinski K, Guyer R, Derome D, et al. Water adsorption in wood microfibril-hemicellulose system: Role of the crystalline–amorphous interface. Biomacromolecules, 2015, 16(9): 2972-2978.
Kulasinski K, Guyer R, Keten S, et al. Impact of moisture adsorption on structure and physical properties of amorphous biopolymers. Macromolecules, 2015, 48(8): 2793-2800.Kulasinski K, Keten S, Churakov S V, et al. Molecular mechanism of moisture-induced transition in amorphous cellulose[J]. ACS Macro Letters, 2014, 3(10): 1037-1040.
Kulasinski K, Keten S, Churakov S V, et al. A comparative molecular dynamics study of crystalline, paracrystalline and amorphous states of cellulose. Cellulose, 2014, 21(3): 1103-1116.