Products used today for wood protection must fulfill to more and more environmental constraints, such as being of low toxicity in answer to the Biocidal Product Directory, but also to involve waterborne treatments to limit rejection of volatile organic compounds in the atmosphere. Boron preservatives have been described as valuable alternatives for wood protection for non-ground contact applications. Disodium octaborate tetrahydrate (DOT), boric acid and borax are the most widely used boron-based wood preservatives. They possess many advantages such as being colourless, odourless, non corrosive, non flammable, inexpensive, having low vapour pressure and low toxicity for mammals and the environment, but suffer of an important drawback due to their high susceptibility to leaching which limits their use in outdoor applications. Numerous studies have been described to reduce boron leachability involving mainly the use of organic chemicals to reduce boron solubility in water through formation of insoluble or hydrophobic complex. However, complexation reduced boron biodisponibility to fungi, limiting the application of such complex to develop antifungal treatment. The objective of this work was to design supramolecular hydrogels, built on low-molecular-weight amphiphilic molecules and containing boron salts conferring fungicidal properties. Mixing boron with thermoreversible hydrogels allows the formation of a supra molecular network incorporating boron and important amount of water upon gelification of the solution when the temperature decreases. Hydrogels obtained from several amphiphilic peptides, pseudo-peptides or various gelling molecules of the same type were impregnated in pine wood block using vacuum pressure treatment and subjected to leaching. Results indicated that incorporation of boron salts in the hydrogel network, allowed to protect effectively wood from degradation caused by the brown rot fungus Poria placenta even after leaching. It was assumed that these hydrogels are able to fill the cell walls and the lumina of the tracheids limiting the leachability of boron salts when the wood is subjected to re-humidification.

Download document (338 kb)
free for the members of IRG. Available if purchased.

Purchase this document