Incorporation of chlorothalonil into polylactic acid-co-polyethylene glycol nanoparticles for rubberwood preservation

Chlorothalonil (CTL), an organic biocide, was successfully incorporated into polylactic acid-co-polyethylene glycol (PLA-PEG) nanoparticles via nanoprecipitation method. The hydrodynamic particle size and CTL loading efficiency of synthesized CTL-PLA-PEG nanoparticles were 12.8 +/- 0.2 nm and 65.9 +/- 0.4%, respectively. Rubberwood (Hevea brasiliensis) samples were treated with 0.025% w/v aqueous suspension of nanoparticles by a vacuum pressure treatment. The studies showed that the pressure and duration needed could be reduced compared to the conventional condition without compromising the effectiveness of the treatment. Good treatability (42.3 +/- 3.4 L m(- 3)) and high chemical retention (8.5 +/- 0.1 kg m(- 3)) were achieved for the wood treated with CTL-PLA-PEG nanoparticles. Biological efficacy performance of the treated wood against subterranean termites (Coptotermes curvignathus), white-rot fungi (Trametes versicolor) and brown-rot fungi (Gloeophyllum trabeum) was evaluated. Weight loss of rubberwood treated with nanoparticles was reduced from 9.7 +/- 0.3% to 3.6 +/- 0.2% in termite test. In addition, CTL-PLA-PEG nanoparticles decreased the weight loss attributed to brown-rot fungi from 37.1 +/- 0.1% to 11.4 +/- 0.4%. As for study with white-rot fungi, weight loss of rubberwood treated with CTL-PLA-PEG nanoparticles decreased from 38.9 +/- 1.0% to 19.2 +/- 0.7%.