Stretchable hydrophobic modified alginate double-network nanocomposite hydrogels for sustained release of water-insoluble pesticides

In agritechnology applications, the sustained release of pesticides plays significant roles in efficient bioavailability and environmental protection. In this study, hydrophobic derivate of sodium alginate (Ugi-SA), polyacrylamide (PAM) and montmorillonite (MMT) were utilized to construct several stretchable double-network nanocomposite hydrogels, which were used to control the release of λ-cyhalothrin. These nanocomposite hydrogels were fully characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The adoption of Ugi-SA and appropriate incorporation of MMT could significantly improve the tensile properties, pesticide-loading efficiency and sustained release performances of the hydrogels. The swelling behavior of all the hydrogels well fits into the Fickian diffusion model. The maximum fracture strain and loading efficiency of the hydrogels reached 2000% and 81.30%, respectively. The hydrogel with 5% MMT content shows the lowest cumulative release percentage of 6.68% over 87 h, and the pesticide release curves well fit into the Weibull model. These novel nanocomposite hydrogels take advantages of both the gelation property of alginate derivatives and the adsorption capacity of clays, to serve as promising potential carriers and to improve the utilization efficiency of water-insoluble pesticides.