Reversible thermothickening of aqueous solutions of polycations from natural origin

This paper concerns our first set of experimental data on alkyl chitosans in acidic medium allowing to compare the roles of the degree of alkylation and that of the length of the alkyl chains on their physicochemical properties in aqueous solution. The balance between electrostatic repulsion (related to the fraction of -NH3+) and the hydrophobic attraction is discussed on the CC12 sample, a chitosan modified with a C-12 aliphatic chain. A phase diagram is established separating the conditions for gel-like structure formation and phase separation. The roles of the net charge and that of the temperature on the formation of hydrophobic aggregates are examined.