Macroporous Hydrogels of Citric Acid-Modified Cellulose Nanofiber via Freeze–Thaw and Post-Cross-Linking Using Metal Ions

High Resolution Image Download MS PowerPoint Slide Macroporous hydrogels have broad applications in various fields including bio-remediation. However, it is still difficult to simultaneously control both the shape and the internal macroporosity. Here, we describe a cellulose-based macroporous hydrogel formed from chemically modified cellulose with citric acid and subsequent freeze–thaw and post-cross-linking method. The nano-fibrillated citric acid-modified cellulose (CACNF) hydrogel with macropores was prepared by freezing the CACNF dispersion and thawing in solutions with metallic salts. This hydrogel features a loose network structure, resulting in high water content (>95%). Additionally, it exhibits remarkable resilience, capable of withstanding 20 cycles of repeated compression while quickly recovering and maintaining consistency in compression strength. Notably, the hydrogel exhibits rapid disintegration under mild conditions such as high pH and the addition of NaCl. This ability enhances its practical usability and ease of artificial processing. This method of using bio-based polymers to produce macroporous hydrogels highlights their versatility in developing functional materials and offers a promising avenue for creating materials with potential applications across various supporting scaffolds which require mechanical and shape recoverability.