Light and temperature dual responsive pesticide release system based on mesoporous silica nanoparticles modified by dopamine

A light and temperature dual responsive copolymer, poly(7-(4-vinylbenzy-loxyl) -4-methylcoumarin-co-N-vinyl caprolactam-co-tri(ethylene glycol)methyl ether methacrylate) (PVNM), was grafted on the surface of dopamine-based mesoporous silica nanoparticles (MSNs). The resulting polymer brush, MSNs-g-PVNM, was characterized by FT-IR, TEM, TGA and XPS. The dual responsive behaviors of MSNs-g-PVNM were systematically studied. With imidacloprid as the model guest pesticide, the loading percentage and loading efficiency of the polymer brush were determined as 9.2% and 40.6%, respectively. The release efficiency of imidacloprid in MSNs-g-PVNM was the lowest value of 5.4% at 20 °C and 365 nm, and it reached the highest value of 52.4% at 50 °C and 254 nm. The loss percentage of imidacloprid on the leaves contained imidacloprid-loaded MSNs-g-PVNM (8.4%) was much less than that contained only imidacloprid (25.2%) after three rinses. It was confirmed that the release process of imidacloprid was well regulated through changing external conditions such as light and temperature.