A structural study of self-assembled chitosan-based sponge materials.

•Structural characterization of treated and untreated biopolymer composites.•Raman structural characterization using dye probes.•Composites were thermally annealed and etched with dye probes in water.•Imaging results reveal structural changes of chitosan-based composites.•Annealing and water intrusion was assessed using Raman microimaging.