Static properties of hydrophobic polyelectrolytes in the thermodynamic limit

A series of hydrophobic sodium poly(styrene-co-styrene sulfonate) of different charge fractions has been studied by static light scattering in the thermodynamic limit. In the examined concentration range (less than or equal to 0.1M/l, in monomers), the solutions show an ideal gas behaviour. A quantitative comparison with previous osmotic pressure measurements reveals the existence of a strong variation of the polarizability, which is related to a change of local chain conformation. This result can be interpreted in terms of the globular instability model for hydrophobic polyelectrolytes (pearl necklace model).