Silver Nanoparticles and Chitosan Oligomers Composites as Poplar Wood Protective Treatments against Wood-Decay Fungi and Termites

This study focuses on Populus &times:euramericana (Dode) Guinier, a globally distributed fast-growing tree. Despite its valuable wood, it exhibits low durability. The aim of this study was to assess the efficacy of a binary composite comprising silver nanoparticles (AgNPs) and chitosan oligomers (COS) in protecting P. &times:euramericana &lsquo:I-214&rsquo: wood against degradation caused by xylophagous fungi and termites through vacuum-pressure impregnation. The test material was carefully selected and conditioned following the guidelines of EN 350:2016, and impregnation was carried out in accordance with EN 113-1:2021. Five concentrations of AgNPs&ndash:COS composites were utilized. Biodeterioration resistance was evaluated based on EN 350:2016 for white (Trametes versicolor (L.) Lloyd) and brown (Coniophora puteana (Schumach.) P.Karst.) rot fungi, and EN 117:2012 for subterranean termites (Reticulitermis grassei Cl&eacute:ment). The durability class and use class were assigned following EN 350:2016 and EN 335:2013, respectively. In comparison to the untreated control, the binary solution at its highest concentration (AgNPs 4 ppm + COS 20 g&middot:L&minus:1) demonstrated a notable reduction in weight loss, decreasing from 41.96 &plusmn: 4.49% to 30.15 &plusmn: 3.08% for white-rot fungi and from 41.93 &plusmn: 4.33% to 27.22 &plusmn: 0.66% for brown rot fungi. Furthermore, the observed termite infestation shifted from &ldquo:heavy&rdquo: to &ldquo:attempted attack&rdquo:, resulting in a decrease in the survival rate from 53.98 &plusmn: 10.40% to 26.62 &plusmn: 8.63%. Consequently, the durability classification of P. &times:euramericana I-214 witnessed an enhancement from &ldquo:Not durable&rdquo: to &ldquo:Slightly&rdquo: and &ldquo:Moderately durable&rdquo: concerning decay fungi and termites, respectively. These findings expand the potential applications of this wood and substantiate the advantages of employing this environmentally friendly treatment.