Controllable Synthesis of Hollow Porous SiO2 Nanoparticles with Tunable Pore Sizes and Their Pesticide Release Kinetic Studies

Pesticides are widely used to ensure crop yields and quality in agriculture. However, most pesticides are easily decomposed, leading to the overuse of pesticides for long-lasting control of pests and diseases, which pose serious hazards to the environment and human health. Herein, we propose a strategy to prepare hollow porous silica nanoparticles (SiO2 NPs) using 1,3,5-trimethylbenzene (TMB) as a pore-expanding agent and CaCO3 NPs as templates. The hollow SiO2 NPs obtain an average particle size of 121 nm and a shell thickness of approximately 15 nm and can be easily prepared with adjustable pore sizes ranging from 1.4 to 4.6 nm without using any surfactants. More importantly, these SiO2 NPs can be used for pesticide encapsulation and controlled release, achieving an encapsulation efficiency of 47% for avermectin and 38% for pyraclostrobin as well as outstanding ultraviolet shielding abilities. Based on the above results, a new release model is built to precisely predict and analyze the pesticide release of SiO2 NPs, showing that the experimental results are consistent with the predicted outcomes, which are further verified by the release performance by the SiO2 NPs with various BET surface areas. Our release model is promising for accurately predicting the drug release performance of hollow porous materials.