Controlling the water uptake of wood by polyelectrolyte adsorption

National and European legal rules and regulations require the replacement of solvent paints by water-born paints. Water on wood surfaces leads to significant problems because water can penetrate the pore system of wood and causes a swelling of the wood. The aim of our work was the reduction of water uptake of wood by polyelectrolytes with the surface polarity and wetting behavior of the wood surfaces should not be significantly changed. Cellulose materials, such as wood show in presence of moderately acidic, neutral or basic aqueous solutions a negative net surface charge. Therefore, for surface modifications of wood samples different commercially available cationic polyelectrolytes were used. In particular, weak polyelectrolytes were likely to reduce the water uptake of wood. They also slightly decrease the surface polarity of wood surfaces, which was advantageous for the rapid wetting of wood. Moreover, the reactive functional groups of the weak polyelectrolytes were used for subsequent cross-linking reactions to form irreversibly anchored polyelectrolyte networks on the wood surfaces.