Thermal curing and addition of essential oils improve structural durability of sustainable sponge-like aerogel for food absorbent pads

This study developed novel sponge-like aerogels from starch, chitosan and citric acid (CA) incorporating cinnamon essential oil (CEO) nanoemulsion representing a biopolymer-based single-material aerogel. Aerogels were fabricated through a combination of freeze-thawing and freeze-drying followed by thermal curing to promote ester crosslinking, with the aim of producing structurally stable superabsorbents with enhanced antibacterial and antifungal functionality. Aerogels exhibited an interconnected porous morphology with porosity ranging from 85.32% to 90.49%. FTIR confirmed CA-mediated ester formation through carbonyl bonds (1714–1717 cm−1), and TGA results demonstrated enhanced thermal stability with reduced final mass loss in cured aerogels. Thermal curing significantly improved the mechanical strength, increasing dry hardness (1180 to 3348 g), improving elasticity in the hydrated state (springiness 0.977 and resilience 0.515), and demonstrating rapid shape recovery within 5 s. Thermal curing and CEO incorporation decreased syneresis, water vapor absorption, and solubility, while enhancing swelling capacity and oil uptake, reflecting enhanced aqueous stability and structural integrity under humid conditions. Aerogels demonstrated antibacterial properties against both Escherichia coli and Staphylococcus aureus (14.88–20.47 mm), and CEO-loaded aerogels maintained vapor-phase antifungal inhibition (13–14 mm) for 15 days against Botrytis cinerea and Aspergillus spp. All aerogels completely degraded in soil within 7–21 days, confirming good biodegradability. Thermally cured and CEO-nanoemulsion-loaded aerogel (CSCA-EO-T) demonstrated a specific combination of high absorbency, mechanical and structural stability (dry and wet-state), antibacterial and antifungal activity, and complete biodegradability properties that are rarely reported together in a biopolymer-based single-material aerogel, highlighting its potential as a sustainable active absorbent pad.