A Polyelectrolyte Complexation Strategy Enabling Tough and Absorbent Chitosan-Based Xerogels via Simple Atmospheric Drying

The structure collapse and performance degradation caused by traditional air-drying technology often hinder the practical application of bio-based xerogels as absorbent pads. In this study, chitosan (CS) and different types of polyanions (carboxymethyl cellulose (CMC), sodium alginate (SA), hyaluronic acid (HA), pectin (PT) and xanthan gum (XG)) in different proportions were used to prepare an xerogel resistant to atmospheric pressure air drying collapse, and its potential as an absorption pad was systematically evaluated. The results showed that among all the treatments, CS/CMC xerogel at an optimal mass ratio of 1:3 demonstrated superior comprehensive properties. It exhibited minimal shrinkage (p < 0.05) and high porosity, coupled with an exceptional water absorption capacity (140% higher than CS/PT) and hardness (96% higher than CS/SA and CS/HA). FTIR and XRD revealed that strong electrostatic interactions and potential amide bond formation between CS and CMC resulted in a dense yet homogeneous network with low crystallinity. SEM imaging further corroborated a uniform thin-walled porous structure. This stable network contributed to high toughness, of CS/CMC significantly surpassing the brittle CS/XG and CS/PT xerogels (p < 0.05). CS/CMC xerogel is an ideal absorbent material with high absorption, stability, and controllable structure.