Near-infrared-light responsive degradable polysulfide pesticide carriers by one-pot inverse vulcanization

Abstract

Functional carriers are appealing materials for pesticide formulations due to their superior role in improving pesticide utilization and reducing environmental pollution. Nevertheless, current carriers often involve tedious chemical synthesis and are time-consuming, which rise potential risks to environment and limit the large-scale industrialization. Here, taking advantage of inverse vulcanization reaction, a near-infrared responsive polysulfide carrier (SOCT) loading tebuconazole (Teb) is prepared in one-pot by using industrial waste sulfur (S8), bio-based soybean oil (SO), and agricultural waste biochar as raw materials. The facile solvent- and surfactant-free processing and the low-cost of raw materials make SOCT be produced easily in kilogram-scale with a loading content of 34.1 wt%. The resulting SOCT exhibits good photothermal property upon irradiation of NIR light, and its release behavior is stable enough against different pH values and coexisting ions, implementing the controlled release of Teb. In vitro and in vivo experiments indicate that SOCT has excellent fungicidal activities against three pathogenic fungi and high biosafety for wheat seed germination and adult zebrafish. In addition, the carrier material is able to be degraded completely in the presence of alkaline or dithiothreitol molecules, due to the available dynamic ester and S-S bonds in polysulfides. These unique features endow our carriers with promising potentials in practical agro-productions. To the best of our knowledge, this is the first time to use inverse vulcanization to prepare carrier materials for pesticides, which provides an effective approach for pesticide formulations with multi-functionality and sustainability.