Environmentally Safe Wood Preservatives

The goal of this Phase I research project is to study a new class of environmentally safe wood preservatives based on cation-anion complexes with antimicrobial activities. The proposed cations include: (1) biguanide/polybiguanide derivatives, (2) polyionenes (polyquats), and (3) quaternary ammonium salts. The associated anions needed to form the complex will be selected from triclosan, tribromophenol, 2-mercaptobenzothiazole, 2-mercapto-pyridine N-oxide, hydrophobic carboxylic acids, and inorganic anions. The combination of both cationic and anionic functions offers potent and broad-spectrum wood preservatives that are safe and could potentially replace currently toxic wood preservatives such as chromated copper arsenate. At least 20 complexes will be tested as wood preservatives against multiple microorganisms using the standard soil-block method. Princeton Trade & Technology, Inc., doing business as Novaflux Technologies, will systematically determine the structure-performance relationship of this new class of wood preservatives. The main tasks include: (1) synthesis and formation of at least 20 cation-anion complexes, (2) development of formulations and methods to ensure their uniform penetration into wood, (3) testing their effectiveness as wood preservatives, and (4) analyses of data to determine effective structure-function trends. The chemical and enzymatic mechanisms involved in wood preservation and decay will be determined and compared with the other classes of preservatives. The proposed complexes are environmentally safe and expected to have significant commercial potential. All of the compounds used to make the complexes have U.S. Environmental Protection Agency and/or U.S. Food and Drug Administration registrations. Successful complexes with the best overall potential as wood preservatives will be identified with the corresponding mechanisms elaborated. Based on structure-performance relationships, further tailoring of molecular structure, developing integrated formulations that may contain a copreservative, and developing an in situ interfacial synthesis for incorporation into wood will be included in future studies. The criteria for selection are: (1) biocidal activity against relevant microorganisms, (2) blocking enzymatic and chemical reaction leading to wood decay, (3) toxicity, (4) leachability, (5) cost, and (6) overall impact on the environment and life cycle. This new class of preservatives is expected to capture a portion of the yearly sales of wood preservatives that are estimated around $3.5 billion.