We investigate in this paper the influence of the improvement of the solvent quality on the structure and the viscous properties of solutions of an hydrophobic polyelectrolyte, poly(styrene-co-sodium styrenesulfonate): PSS. The solvent used is a mixture of water and an organic solvent, THF, which is also slightly polar. We use small angle neutron scattering in the semidilute regime and viscosimetry as a function of concentration in dilute and semidilute unentangled regime. The structure, namely the scattering from all chains, is characterized by a maximum ("polyelectrolyte peak"). Its position and amplitude depends, at a given sulfonation rate of PSS, on the solvent quality through the added amount of organic solvent (THF). These evolutions with the THF amount are more pronounced when the sulfonation rate f is low (more hydrophobic polyelectrolyte) and the amount of added THF is high. Adding THF to hydrophobic PSS (f = 0.50 or f = 0.38), diminishes also the "shoulder" visible in the log I - log q plot and associated with the pearl size. It is therefore proposed that when THF is added to aqueous polyelectrolyte solutions, the pearls are dissolved and the chain conformation evolves from the pearl-necklace shape already reported in pure water toward the string-like conformation in pure water for fully sulfonated PSS. An addition of THF also reduces the important low q upturn found with hydrophobic polyelectrolyte solutions: the large aggregates are dissolved by THF. The upturn can become for PSSNa f = 0.38, after adding enough THF (50%), even smaller than that for the charged hydrophilic case PSSNa f = 0.82, in water. This can mean that in the quasi-fully charged PSS at f = 0.82 there are still hydrophobic effects in water, which is disagreeing with our recent reports, or that the electrostatics contribution to the upturn is reduced due to a lower dielectric permittivity. Concerning the hydrophilic polyelectrolyte, poly(sodium-2-acrylamido-2-methylpropanesulfonate)-co-(acrylamide): AMAMPS, no evolution in structure occurs until 25% THF. The viscosimetry variation with THF fraction is in good agreement with the scattering one up to 25%: though little dependent on THF for AMAMPS, and for hydrophilic PSSNa, it increases for hydrophobic PSSNa in agreement with the chain expansion signaled by scattering. At 50% THF concentration, the hydrophilic polyelectrolyte shows new surprising behaviors: the scattering of PSSNa is no longer characteristic of polyelectrolytes, and AMAMPS solutions display an unexpected viscosity decrease.

Aggregates-a phenomenon still not understood-as well as the pearl-necklace-like chain conformation in aqueous solutions of hydrophobic polyelectrolytes are addressed here, using treatment by an organic solvent. The second appear to be at equilibrium in water. The first appear to be metastable, and surprisingly associated with higher zero shear viscosity. The hydrophobic polyelectrolyte is poly(styrene-co-sodium styrenesulfonate) (PSS), and the solution treatment is to first add to water an organic solvent, THF, which is then evaporated and replaced by the same amount of water. To investigate polyelectrolyte solutions as a function of THF treatment, we use small angle neutron scattering in the semidilute regime, viscosimetry in the dilute and semidilute regimes (unentangled), and osmometry in the similar semidilute regime (the contribution of the counterions being dominant). First, the structure, namely, the scattering from all chains, is characterized by a maximum ("polyelectrolyte peak"). Its position, amplitude, and scattered intensity at zero angle depend, at a given sulfonation rate of PSS, on the solvent quality through the added amount of organic solvent (THF). This dependence is very pronounced when the sulfonation rate is low (more hydrophobic polyelectrolyte) and is canceled when the sulfonation rate is high (more hydrophilic polyelectrolyte). Second, the viscosity of the polyelectrolyte solutions decreases with THF treatment for the hydrophobic polyelectrolytes. Third, osmometry shows no noticeable increase of the effective charge with THF treatment. It is proposed that the large scale aggregates, especially in the case of very hydrophobic polyelectrolytes, disappear irreversibly with THF treatment, while the pearl-necklace conformation of the chain remains as in its initial state. Parallel test measurements for a fully hydrophilic polyelectrolyte, poly(sodium-2-acrylamido-2-methylpropanesulfonate)-co-(acrylamide) (P(AMAMPS)), at different sulfonation rates, show no evolution of the structure with THF treatment in the aqueous solution. The same behavior is highlighted by viscosimetry.

In this erratum, we wish to make clear the value of the exponent in the dependence of q* with the dielectric constant ε. Equation 5, which specifies q* ∼ ε +1/7 is right. Conversely, in the fourth line of the paragraph under eq 5, the expression q* ∼ ε −1/7 is wrong; the minus sign should be removed.We also specify (section III-1-A, first paragraph, sixth line) that the number of units per chain, equal to 2838, is a weight average number.