Nanoparticles containing the fungicides tebuconazole or chlorothalonil were prepared with median diameters of ϳ 100 -25 0 nm. The nanoparticle matrices were polyvinylpyridine (PVP), copolymers of PVP and styrene (PVP-co-St), and blends of PVP and hyperbranched polyesters (HBPs). The isolated nanoparticles were resuspended in water to yield suspensions able to deliver 0.1, 0.2, 0.4, and 0.8 kg fungicide/m 3 of wood. Southern yellow pine (SYP) was treated with these suspensions using conventional vacuum-pressure treatments. Less concentrated suspensions delivered the nanoparticles quantitatively into the SYP while suspensions capable of delivering up to 0.8 kg of the fungicide (the active ingredient or AI) per cubic meter of SYP delivered 0.4 -0.7 kg AI/m 3 , depending on the nanoparticle matrix. The SYP lost less than 5% of its mass after 55 days of exposure to Gloeophyllum trabeum when the tebuconazole content in the SYP reached 0.2 kg/m 3 , and the matrix identity had little effect on the results. The SYP lost between 3 and 6% of its mass after 55 days of exposure to G. trabeum when the AI was chlorothalonil at a level of ϳ 0.6 kg AI/m 3 of wood and was introduced into SYP in nanoparticles with a PVP/HBP matrix, but it lost ϳ 11% of its mass at the same AI levels when the nanoparticle matrix was PVP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 596 -607, 2002
Biocide-containing nanoparticles were suspended in water to prepare wood treating suspensions able to deliver up to 0.8 kg biocide/m 3 of wood. The nanoparticle preparation method was versatile, and three fungicides (tebuconazole, chlorothalonil, and KATHON 930) and one insecticide (chlorpyrifos) were incorporated into the nanoparticles with little customization of the preparative method. Greater customization was required when the polymer matrix was changed, but the method was generally robust; nanoparticles could be prepared from several different polymers, copolymers, and polymer blends. The median nanoparticle size increased as the matrix hydrophobicity increased. Nanoparticles were quantitatively delivered into birch and southern yellow pine (SYP) at low suspension loadings, but the delivery efficiency decreased with increased suspension loading and with increased matrix hydrophobicity. The delivery efficiency was also less for birch than for SYP. Undelivered nanoparticles were found to have undergone aggregation. Greater aggregation occurred in the more hydrophobic formulations than in the hydrophilic formulations. High biological efficacy was found for all the biocides tested. Nanoparticle-treated birch was exposed to Trametes versicolor for 55 days and some protection was afforded, even at biocide loading levels of only 0.1 kg/m 3 . At the highest loadings (ϳ0.6 kg/m 3 ) the weight loss after exposure to T. versicolor was generally ϳ10% for most formulations. The SYP was treated with KATHON 930 in polyvinylpyridine. At levels of 0.1 kg of biocide/m 3 of wood less than 5% of the SYP mass was lost after 50 days of exposure to Gloeophyllum trabeum.
Polymeric nanoparticles containing the fungicides tebuconazole and chlorothalonil were prepared by a simple, surfactant-free method and found to have significantly smaller median particle diameters and more stable aqueous suspensions than their surfactant-stabilized counterparts. These more stable suspensions were delivered into southern yellow pine and birch wood with greater efficiency than the equivalent surfactant-stabilized nanoparticle suspensions. We found that the suspensions protected the treated wood against fungal attack by Gloeophyllum trabeum, a common brown rot wood decay fungus, and Trametes versicolor, a common white rot wood decay fungus, at low tebuconazole and chlorothalonil contents in the wood. Southern pine lost 5% or less of its mass after 55 days of exposure to G. trabeum when the tebuconazole or chlorothalonil content in the wood was only 0.4 kg/m 3 , while a tebuconazole or chlorothalonil content of 0.8 kg/m 3 in birch wood was sufficient to bring its mass loss to less than 5% after 55 days of exposure to T. versicolor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 615-621, 2002
The fungicides tebuconazole and chlorothalonil were successfully incorporated into polymeric nanoparticles with median particle diameters of 100–250 nm. Polyvinylpyridine (PVPy) and polyvinylpyridine‐co‐styrene (10% styrene and 30% styrene) were employed as the polymer matrix. The size of the nanoparticle increased with increased styrene content. The biocide also affected particle size, with chlorothalonil consistently yielding larger nanoparticles than tebuconazole. The release of the biocides from the polymeric nanoparticles was studied by suspending them in water. The release rate of both tebuconazole and chlorothalonil decreased with increased styrene content in the matrix, and chlorothalonil consistently released more slowly from the polymeric nanoparticles than did tebuconazole. It was found that biocides were successfully introduced into solid wood by incorporating them within polymeric nanoparticles, suspending the nanoparticles in water, and using the suspension to treat the wood with conventional pressure treatments. Once in the wood, the polymer matrix serves as a reservoir for the biocide and controls its release rate into the wood. Southern pine sapwood samples were treated with biocide‐containing nanoparticles suspended in water, then exposed to the wood decay fungus Gloeophyllum trabeum using a simple wafer test. Samples exhibited fungal resistance at appropriate levels of biocide incorporation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 458–465, 2001
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