(10) Solubility of chitosan
1. The solution properties of a chitosan depend on
① Its average DA
② Distribution of the acetyl groups along the main chain
③ The molecular weight
2. The deacetylation gives an irregular structure due to the semicrystalline character of the initial
polymer
3. Degree of ionization depends on the pH and the pK of the acid
① Solubilization of chitosan with low DA occurs for an average degree of ionization
② Solubility also depends on the ionic concentration
4. The solubility is a very difficult parameter to control
- It is related to : DA, the ionic concentration, the pH, the nature of the acid used for protonation,
the distribution of polysaccharide
5. Water-soluble form of chitosan at neutral pH was obtained in the presence of glycerol 2-phosphate
(11) Solvent and solution properties
1. Chitin and chitosan degrade before melting, which is typical for polysaccharides with hydrogen
bonding
2. It necessary to dissolve chitin and chitosan in an appropriate solvent system to impart functionality
3. The maximum amount of polymer is dissolved in a given solvent towards a homogeneous solution
4. The polymer is regenerated in the required form
- A coagulant is required for polymer regeneration or solidification