Starch-cellulose-gelatin hydrogels obtained by reactive extrusion aiming an ecologically friendly perspective

Abstract

Abstract Biopolymeric hydrogels represent a versatile class of materials with a wide range of potential applications, including their use in agricultural materials, drug delivery systems, biosensors, and food packaging. This investigation primarily centered on the synthesis and characterization of biodegradable hydrogels based on starch, cellulose, and gelatin, acting as a polymeric matrix intended for water retention in agricultural contexts. Prior to their incorporation into the hydrogels formulations, cassava starch and cellulose extracted from oat hulls underwent modification via reactive extrusion involving reaction with citric acid (CA) and sodium trimetaphosfate (STMP) as crosslinking agents, respectively. The hydrogels were obtained through a reactive extrusion process to produce porous pellets. These pellets were characterized according to their porosity, thermal properties, degree of swelling at different times and pHs, and water adsorption capacities. The hydrogel sample formulated with both CA-modified starch and STMP-modified cellulose, and gelatin, presented the highest values of porosity (> 45%) and open pores (> 5%), and the higher degree of swelling (607%). These materials as promising candidates for application in agriculture to increase water and/or fertilizers retention capacity in soil, with important advantages, including their biodegradability and low toxicity. It is worth mentioning that the reactive extrusion process used is a continuous process, with low effluent generation and scalable for large-scale production.