Rheological Properties of Carboxymethyl Cellulose Solutions and Gels: An Overview

ABSTRACT

We present an overview of the main rheological phenomena associated with solutions and gels of carboxymethyl cellulose, a widely used ionic cellulose ether. When the number of carboxymethyl groups per monomer (DS) exceeds a value of ≃1, chains behave as hydrophilic polymers with weak associative interactions. Their behavior is similar to that of other semiflexible polyelectrolytes. For lower degrees of substitution, unsubstituted patches along the chains act as temporary stickers leading to associative solution rheology and weak gel formation at high concentrations. The influence of environmental parameters such as temperature, pH and added salt content is discussed and the rheological properties of mixtures of NaCMC with surfactants and colloids are reviewed. Open questions are highlighted and discussed. The main limitation of the current literature is that rheological phenomena are correlated with average properties (average DS, average molar mass), without quantifying heterogeneity in those parameters. Establishing quantitative links between substitution pattern, molar‐mass distribution, aggregation state, and rheological response is the main challenge for developing a predictive understanding of CMC solutions and gels.