Synthesis of polypyrrole-modified gelatin/poly (acrylic acid) semi-interpenetrating network hydrogel and its controlled release of agrochemicals based on helix–coil transition of gelatin

Stimuli-responsive controlled release system is an effective way to increase the efficiency of agrochemicals and reduce environmental pollution. In this work, a novel polypyrrole@gelatin/poly (acrylic acid) (PPy@Gel/PAAx) hydrogel with a semi-interpenetrating network structure was synthesized by gelatin, polypyrrole (PPy) and acrylic acid (AA). The structure and property of the hydrogel were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy and infrared imaging. The efficiency of the controlled release system was systematically studied by using carbendazim as a template drug. The results indicated that PPy@Gel/PAAx not only has outstanding light-sensitive property, but also has good water retention performance. Therein, PPy used as a light-sensitive component, could convert the absorbed light energy into heat energy. This kind of photothermal conversion could lead to helix-coil structural transition of gelatin which promotes the release of carbendazim by changing the pore diameter of the hydrogel. Consequently, excellent controlled-release capacity and water retention performance enable PPy@Gel/PAAx hydrogel to be a potential candidate in agricultural application.