Helicity degree of carrageenan conformation determines the polysaccharide and water interactions

The polysaccharide in solution at critical concentration, Cc (g/L), is assimilated to a nano hydrogel (nHG) made of a single polysaccharide chain. Taking as reference the characteristic temperature of 20 +/- 2 degrees C at which kappacarrageenan (kappa-Car) nHG swelling is greater with a Cc = 0.55 +/- 0.05 g/L, the temperature of the minimum deswelling in the presence of KCl was found at 30 +/- 2 degrees C for 5 mM with a Cc = 1.15 +/- 0.05 g/L but not measurable above 100 degrees C for 10 mM of which Cc = 1.3 +/- 0.05 g/L. Lowering the temperature to 5 degrees C, contraction of the nHG and further coil-helix transition with self-assembly increases the sample's viscosity, which steadily evolves with time in a logarithmic scale. Accordingly, the relative increment of the viscosity per unit of concentration, Rv (L/g), should increase in agreement with increasing polysaccharide concentration. But the Rv decreases for kappa-Car samples above 3.5 +/- 0.5 g/L in the presence of 10 mM KCl under steady shear 15 s-1. This reflects a decrease of kappa-Car helicity degree knowing that the polysaccharide is rather hydrophilic when its helicity degree is the lowest.