Enzymatic grafting as a method for wood coating

Wood is a natural material with structural and aesthetic roles in indoor and outdoor constructions. Wood treatments are performed to improve the material's natural drawbacks, such as biodeterioration, water absorption, microbial colonization, and flame sensitivity.

Conventional wood treatments, especially when wood is used outdoors, must normally be repeated regularly, because the compounds that are used are leached away, since a stable link between the wood and chemicals added is lacking. This leaching may also produce environmental pollution.

To improve the stability of wood treatments by promoting a stable coating, a new biotech method is proposed: the use of laccase to stably graft chemical compounds onto a wood surface. Laccase is an enzyme that can oxidize phenolic compounds to produce chemical radicals that may then link to a polymer chain, such as wood components, by means of covalent bonding. If the phenolic compounds also contain another functionality, it could be conferred to the wood after the grafting. This principle has been used to link several phenolic compounds to wood samples and, therefore, to modify their chemical composition and properties.

Using this biotechnological tool, a range of wood treatments were tested and analysed: the modification of the surface composition of wood, the hydrophobization of wood surfaces, the grafting of flame retardants, the design of new wood durability treatments, etc.

This new method opens up new possibilities in wood treatments by means of a mild and sustainable process.