A flexible modulated pesticide release platform through poly(urethane–urea) microcapsules: effect of different crosslinkers compositions

Abstract BACKGROUND Polymeric microcapsules (MCs) have become an important issue and have attracted increasing attention because of their tunable physical and chemical properties. Diverse shell structures can confer multiple properties on MCs. RESULTS Different polyols (1,4‐butanediol and glycerin) and polyamines (triethylenetetramine and isophorondiamine) were selected as crosslinkers to obtain emamectin benzoate (EB)‐loaded poly(urethane–urea) MCs (PU‐MCs) by interfacial polymerization. The four obtained PU‐MCs showed sphericity with different degrees of smoothness on their surfaces, and displayed a uniform size distribution ranging from 500 to 700 nm. Moreover, transmission electron microscopy showed that the shell thickness was roughly uniform, and was greatly influenced by the type and structure of the crosslinker. GI‐MCs, prepared using glycerin and isophorondiamine, had the largest shell thickness. GT‐MCs, obtained using glycerin and triethylenetetramine, had the highest encapsulation efficiency and drug‐loading content, and BT‐MCs, obtained using mixtures of 1,4‐butanediol and triethylenetetramine, had the fastest release behavior. Thermogravimetric analysis revealed that the greater the degree of shell crosslinking, the higher decomposition temperature and the greater the thermal stability. A BT‐MC suspension had the lowest viscosity and contact angle with the best wettability. Bioassay experiments showed that BT‐MCs exhibited good insecticidal activity against Plutella xylostella larvae with a half‐maximal lethal concentration of 4.19 mg/L. Furthermore, a BT‐MC suspension showed good thermal and light stability, with potential applications in minimizing the toxicity of EB through sustained release. CONCLUSION Various properties of EB‐loaded PU‐MCs were modulated through simple selection of different polyols and polyamines during fabrication, which might have an important role in constructing the pesticide delivery system and improving pesticide utilization. © 2024 Society of Chemical Industry.