Thermo-Responsive Behavior of Enzymatic Hydrolysis Lignin in the Ethanol/Water Mixed Solvent and Its Application in the Controlled Release of Pesticides

Enzymatic hydrolysis lignin (EHL) has special solubility in the ethanol/water mixed solvent. In this paper, it is found that the temperature affects the intramolecular and intermolecular forces of lignin as well as the interaction between lignin and solvent molecules, which makes them have an upper critical solution temperature behavior in ethanol/water. Furthermore, avermectin-loaded EHL microspheres (AVM@EHL MPs) with an average particle size of 800 nm and uniform distribution were prepared through the anti-solvent method. The simulated pesticide release experiment of AVM@EHL MPs in ethanol/water showed that the drug release amount was only 20% at 25 °C for 24 h, while at 50 °C, the drug release amount of 24 h was as high as 90%, indicating that the release of drug-loaded microspheres in ethanol/water was temperature-responsive.