When the degree of deacetylation of chitin
reaches about 50% (depending on the origin of
the polymer), it becomes soluble in aqueous acidic
media and is called chitosan. The solubilization
occurs by protonation of the –NH2 function on the
C-2 position of the D-glucosamine repeat unit,
whereby the polysaccharide is converted to a
polyelectrolyte in acidic media. Chitosan is the only
pseudonatural cationic polymer and thus