Thermodynamics of polysaccharide polyelectrolytes: Enthalpy changes in the conformational transition of κ-carrageenan

An approach, based entirely on Counterion Condensation (CC) polyelectrolyte theory and on thermodynamic consideration, is used to derive the ionic and the non-ionic energy contributions for processes involving the conformational transition of a linear polyelectrolyte. As an example of application, the conformational transition of the algal polysaccharide, K-carrageenan, is analysed. This anionic polymer undergoes a fhermoreversible disorder-order conformational transition which parallelsspecijk binding of cations (as K +, Cs+, ...) and, quite unusually, of the iodide anion.Experimental data on the conformational process and on the binding process will be compared with the theoretical prediction.