Effect of a Surfactant on Fabrication and Released Property of Nanopesticides Based on a Covalent Organic Framework

The triaminoguanidine covalent organic framework (COF) has abundant cationic charges, excellent stability, and strong adsorption capacity, which make it become a potential drug release carrier. In this study, two kinds of COFs, COF1 and COF2, were prepared by reacting triaminoguanidine hydrochloride with 2,5-dihydroxyp-benzaldehyde and 3,3′-dihydroxyl-[1,1′-biphenyl]-4,4′-diformaldehyde, respectively, and then the COF was combined with dinotefuran (DIN)-solubilized surfactant (S) micelles to obtain a series of DIN@S-COF nanopesticides. The effect of S on the structures of S-COF and DIN@S-COF was investigated by XRD, FT-IR, TGA/DTA, contact angle, SEM, and BET methods. The pore diameter of COF2 (2.4 nm) was higher than that of COF1 (1.6 nm). The pore sizes of S-COF1 and DIN@S-COF1 were obviously larger than that of COF1, and those of S-COF2 and DIN@S-COF2 were changed. The effect of S on the release behavior of DIN@S-COF was also investigated and discussed. DIN@DSS (SDS, MADS, AOT)-COF1 and DIN@AOT-COF2 displayed a sustained release behavior. The release behavior was mainly influenced by the pore diameter of the COF, surfactant structure, and the attractive interaction between COF, S, and DIN. The DIN release from the composite could be well fitted by parabolic diffusion and pseudo-second-order models. COFs had the potential application as a new and efficient pesticide delivery system.