This interactive visual shows how varying the Molecular Weight (MW) & Degree of Deacetylation (DDA) shape chitosan’s behavior in acidic solution.
Key Definitions
- Backbone (sugar units): The repeating “spine” of the polymer.
- Amine groups (blue): –NH₂ on glucosamine units. In acid, these groups become positively charged –NH₃⁺.
- Acetyl groups (green): –NHCOCH₃ on N-acetyl-glucosamine units. These bring non-polar, hydrophobic character.
- DDA (Degree of Deacetylation): The fraction (%) of monomers that carry an amine group instead of an acetyl group.
- MW (Molecular Weight / Chain Length): How many monomer units per polymer chain; longer chains = higher MW.
| Condition | What happens | What you see in the visual |
| Low DDA (< ~60 %) | Many acetyl units → many hydrophobic patches. Chains lose charge. | Polymer becomes insoluble. Chains tend to fold, aggregate, and clump together (= chitin). |
| High DDA (> ~60 %) in acidic pH | Many amines → many positive charges. Chains repel each other electrostatically. | Polymer becomes soluble. Chains form expanded, separated coils due to repulsion |
| Low MW (short chains) | Chains are small, flexible, fewer entanglements. | Low viscosity. Easy to handle, good for sprays and simple mixing. |
| High MW (long chains) | Chains are long, overlap and entangle. | High viscosity. Solution becomes thick, suitable for gels and film formation. |
