Nanofibril Cellulose–Carrageenan Aerogel Production and the Effect of Crosslinker Addition on Aerogel Performance

Nanofibrillated cellulose (NFC) and carrageenan (CG) have emerged as sustainable biological polymers of plant and animal origin, and have been produced as films, spheres, and other materials with various physical macromorphological structures. However, to the best of the authors’ knowledge, NFC/CG aerogels combining TEMPO-oxidized NFC, CG, and a natural crosslinker (TA) have not been systematically characterized yet, which is the main objective of this study. NFC/CG aerogels were obtained by combining these two polymers at various mixing ratios. Samples were produced as pure aerogels without crosslinking chemicals and with tannic acid (TA) as a crosslinker. Material performance was evaluated using density–porosity, BET (Brunauer–Emmett–Teller) surface area, liquid absorption (water, phosphate-buffered saline (PBS), oil, methylene blue (MB), and Congo red (CR) penetration ratio), water vapor transmission (WVTR), chemical structure changes (FTIR), degree of crystallinity (XRD), antibacterial properties, and SEM (scanning electron microscopy) imaging tests. All aerogels exhibit densities of 0.0154–0.0267 g/cm3, porosities of 97.91–99.63%, and specific surface areas of 128–303 m2/g. In addition to bacterial resistance, aerogels had high water and PBS absorption values. The incorporation of TA led to a notable enhancement in antibacterial efficacy, though with a minor decrease in the porosity and surface area parameters.