Acid-Induced Gelation of Carboxymethylcellulose Solutions

The present work offers a comprehensive description of the acid-induced gelation of carboxymethylcellulose (CMC), a water-soluble derivative of cellulose broadly used in numerous applications ranging from food packaging to biomedical engineering. Linear viscoelastic properties measured at various pH and CMC contents allow us to build a sol–gel phase diagram and show that CMC gels exhibit broad power-law viscoelastic spectra that can be rescaled onto a master curve following a time–composition superposition principle. These results demonstrate the microstructural self-similarity of CMC gels and inspire a mean-field model based on hydrophobic interchain association that accounts for the sol–gel boundary over the entire range of CMC content under study. Neutron scattering experiments further confirm this picture and suggest that CMC gels comprise a fibrous network cross-linked by aggregates. Finally, low-field NMR measurements offer an original signature of acid-induced gelation from a solvent perspective. Altogether, these results open avenues for the precise manipulation and control of CMC-based hydrogels.