Dual-responsive bagasse cellulose/PVA hydrogels for sustained release of plant growth regulator

Agrochemicals play an irreplaceable role in the process of agricultural production. However, unreasonable use of agrochemicals can cause serious harm to the environment. Therefore, the controlled release of agrochemicals is critical in the sustainable development of agriculture and benefiting the environment. In this work, a composite hydrogel was prepared from dialdehyde cellulose and reinforced by polyvinyl alcohol (PVA) while cysteamine dihydrochloride acted as a cross-linking agent to render the hydrogel pH and redox-responsive for the controlled release of a model agrochemical, i.e., salicylic acid (SA). The aldehyde content in the modified cellulose reached 10.65 mmol/g while the yield of oxidized cellulose was 55%. The structure, morphology and properties of the composite hydrogels were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). In addition, the release behavior of SA loaded in the hydrogels under various different conditions was also studied. The results showed that the addition of PVA could improve the mechanical properties of hydrogels, and the cumulative release of SA could be modulated by varying release conditions or environmental stimuli; and the release kinetics was well fitted with the Korsmeyer-Peppas model. Moreover, the release of SA could be promoted under acidic conditions and in the presence of reducing agent glutathione (GSH). The findings from this work particularly benefit the agricultural production.