Is chitosan hydrophilic or hydrophobic? What is the essence?

Chitosan is a kind of polysaccharide and should be regarded as a hydrophilic substance. But chitosan is insoluble in neutral aqueous solution, but soluble in acidic pH water. Chitosan with large molecular weight is generally about 6.5438+0.5 million. When its concentration in aqueous solution is 2%, it has become a gel. If the molecular weight of chitosan is very small, it can also be dissolved in neutral aqueous solution.