A structural study of self-assembled chitosan-based sponge materials.
Uncontrolled dissolution in solvent media is a key challenge related to the utility of chitosan composite materials. Thermal annealing offers a solution to address this problem. However, conventional characterization methods pose limitations regarding key structural features, especially for carbohydrate materials that possess similar biopolymer components. Herein, self-assembled chitosan-based sponges were prepared with and without annealing to compare their structural and physicochemical properties. The utility of Raman micro-imaging is reported with dye probe etching as an effective and facile method to reveal structural features for chitosan-based composite materials, before and after thermal annealing. We proposed that such composites undergo a structural change from a loosely packed to a more densely packed structure. As well, the multi-functional role of polyethylene oxide in the composites and the potential role of solvent etching was evaluated. The improved stability of the treated composites reveals their potential utility for applications in aqueous media.