Chemical, colloidal and mechanical contributions to the state of water in wood cell walls

Abstract

The properties of wood depend strongly on its water content, but the physicochemical basis for the interaction of water with cell wall components is poorly understood. Due to the importance of the problem both in the context of wood technology and the biological function of swelling and dehydration for growth stresses and seed dispersal, a wealth of descriptive data has been accumulated but a microscopic theory of water-biomolecular interactions is missing. We develop here, at a primitive level, a minimal parameter-free, coarse-grained, model of wood secondary cell walls to predict water absorption, in the form of an equation of state. It includes for the first time all threemechanical, colloidal and chemical-contributions, taking into account the cell walls microstructure. The hydration force around the elongated cellulose crystals and entropy of mixing of the matrix polymers (hemicelluloses and lignin) are the dominant contributions driving the swelling. The elastic energy needed to swell the composite is the main term opposing water uptake. Hysteresis is not predicted but water uptake versus humidity, is reproduced in a large temperature range. Within this framework, the origin of wood dissolution and different effects of wood treatments on water sorption can be understood at the molecular level.

Tight cohesion between glycolipid membranes results from balanced water–headgroup interactions

“…Finally, sugar–water interactions are not only relevant for glycolipids but also in a much broader context ranging from sugar solutions40 and sugar surfactants4142 to glycoproteins and sugar-based biomaterials43. Some of the concepts presented here may also apply to those problems.…”

Impregnation and Swelling of Wood with Salts: Ion Specific Kinetics and Thermodynamics Effects

“…[31] Starting from the cell wall microstructural model described in Figure 1, structure and composition of the material are taken into account to develop a model with chemical and mechanical contributions to predict the effects of ions adsorption and resulting charge separation. [31] Starting from the cell wall microstructural model described in Figure 1, structure and composition of the material are taken into account to develop a model with chemical and mechanical contributions to predict the effects of ions adsorption and resulting charge separation.…”

“…Water uptake in wood and relation between anisotropic swelling and osmotic pressure variations can be represented by a general Equation of State, that links OP to the distance between the cellulose crystals in wood cell wall materials. [31] Starting from the cell wall microstructural model described in Figure 1, structure and composition of the material are taken into account to develop a model with chemical and mechanical contributions to predict the effects of ions adsorption and resulting charge separation. The force balance leads to the development of the EOS, in which molecular and macroscopic forces between wood building blocks, that are responsible for the solvent uptake, are Adv.…”

“…The first step in terms of free energy for the ions adsorption quantification is made by the following evaluation, [31] with and without the electrostatic term due to charge separation. One of the ions is bound via a binding constant K to a site.…”

Composition dependent Equation of State of cellulose based plant tissues in the presence of electrolytes

“…This swelling behavior can be expressed in terms of Equation of State (EOS) as it has been recently established. [1] Equations of state can be expressed either using quantities typical of chemical and materials engineering, i.e. the water content versus relative humidity, or in quantities used in physical chemistry, i.e.…”