Investigating the Structure-Related Properties of Cellulose-Based Superabsorbent Hydrogels

Superabsorbent hydrogels are macromolecular networks able to absorb and retain large amounts of water solutions within their fine mesh-like structure. More importantly, they are capable of multiple swelling/shrinking transitions in response to specific environmental cues (e.g., pH, ionic strength, temperature, presence of given electrolytes), thus exhibiting a stimuli-sensitive behavior, which makes them appealing for the design of smart devices in a number of technological fields. In particular, in the last two decades, cellulose-based superabsorbent hydrogels have proven to be an environmentally friendly and cost-effective alternative to acrylamide-based products. This chapter reviews the relationship between the molecular structure of cellulose-based hydrogels and their physicochemical properties. First, the network formation through the use of different cellulose derivatives and chemical or physical crosslinking agents is presented. Successively, the smart swelling capability of the hydrogels as a function of composition and structure is thoroughly discussed. Finally, several approaches to the hydrogel characterization are reviewed, with focus on the assessment of key mechanical, thermal and morphological properties.