Wood surface functionalisation by means of atmospheric plasma pressure polymerization

Due to growing environmental concerns, industry and research institutes are searching for new methods of wood protection in order to substitute conventional preservatives based on creosotes or copper, chrome and arsenic (CCA), and to obtain longer lasting treatments for decreasing maintenance needs. The aim of the research is to develop economically sustainable and environmental friendly process in order to obtain a long life protection against water and weathering degradation. Lignocellulosic materials are three dimensional biopolymer composites primarily made of cellulose, hemicelluloses and lignin: the most abundant functional groups of cellulosics polymers is the hydroxyl group followed by other oxygen functionalities that attract water trough hydrogen bonding. Water-wood interactions can lead to dimensional instability and accelerated bio-, as well as weathering degradation. Atmospheric cold plasma treatments are known as powerful techniques in order to obtain time-stable specific surface functionalities. Furthermore plasma-induced surface modifications are dry processes preventing use of toxic or corrosive chemicals. Plasma induced functionalities are confined only at the outermost surface layer of the, thus not varying the bulk properties of treated materials. It is also known that an increase in the crystallinity and orientation of plasma-polymerised layers reduces mobility of polymer chains, resulting in slower aging. Several types of materials such as heart-wood, laminate wood, plywood and marine plywood as well as different surface functionalities (hydrophily, hydrophoby, fireresistance) are being investigated by means of both plasma activation and plasma polymerizations steps.