Impact of freezing on the properties of biodegradable sponges from modified starch: Optimization and characterization

The excessive use of petroleum-derived plastics has generated a growing environmental concern due to the accumulation of microplastics in various ecosystems. Corn starch is a promising alternative for the development of biopolymers. However, starch in its native state presents limitations on its physicochemical properties for various industrial applications, requiring the modification of the polymeric components of the starch granule. In this study, biodegradable sponges were developed from corn starch modified by acid hydrolysis. The optimal drying conditions were determined using response surface methodology. The variables evaluated were the swelling ratio (%) and the crosslinking density (mol·cm 3 ). The modified starch and sponges obtained were characterized by FT-IR, SEM, ζ potential, particle size distribution and water desorption kinetics, as well as in vitro biodegradation respectively. Optimal sponge synthesis required a 3.2 N HCl concentration and a drying temperature of -20 °C, the water absorption of the optimal sponges retained water at ≥ 40 mL. The swelling ratio and crosslinking density presented values of 2.82 and 6.12 mol·cm 3 respectively. Biodegradability tests demonstrated total disintegration of the sponge compared to the control with a biodegradability rate of 94%. These results suggest its potential use in biodegradable packaging and absorbent products, contributing to the development of sustainable alternatives to synthetic polymers and reducing their environmental impact.