Incorporation of permethrin into chitosan polymeric nanoparticles using nanoprecipitation method for rubberwood preservation against termite attack

Permethrin-loaded chitosan nanoparticle was successfully synthesised through the nanoprecipitation method. The hydrodynamic particle size and permethrin loading efficiency of the synthesised permethrin-chitosan nanoparticles were 199.7 ± 6.4 mm and 84.6 ± 2.20%, respectively. Hevea brasiliensis samples were then treated with 0.0025% w/v aqueous suspension of nanoparticles by vacuum pressure treatment. The optimisation studies proved that the pressure and duration of wood treatment with the permethrin-chitosan nanoparticles could be halved (100 psi and 60 min) as compared to the previously used standard condition (200 psi and 120 min). Results depict that the treatability and chemical retention achieved by the H. brasiliensis treated with permethrin-chitosan nanoparticles was 355.12 ± 9.50 L m−3 and 8.23 ± 1.23 kg m−3, respectively. Meanwhile, the weight loss of treated H. brasiliensis with permethrin-chitosan nanoparticles against subterranean termites; Coptotermes curvignathus reduced from 7.35 ± 0.080% to 1.20 ± 0.340%, whereas the visual rating increased from very severe attack to trace only (surface nibbles permitted). Findings from this study indicated that polymeric nanoparticles of chitosan could act as a carrier to deliver the permethrin into H. brasiliensis through water-based vacuum pressure treatment and also provide good protection against termites.