Static light scattering and electric birefringence experiments on saltfree solutions of poly(styrenesulfonate)

Anomalous Concentration Effects of Zwitterionic Telechelic Polymer Solutions in Electric Fields

“…With increasing concentration the relaxation time increases, even though the sign of the birefringence changes. This is clearly different from the behaviour of PSS found by Kramer and Hoffmann [52] and Johner et al, [53] where similar anomalous behaviour is coupled with a decrease in relaxation times. By contrast, within experimental limit, s 1 is independent of field strength, concentration and also molecular weight, and is therefore unaffected by the aggregation to gelation phenomena suggested by the change in sign of the birefringence.…”

“…The measured s 2 values for 34.7 6 10 3 ZT-PS are comparable to those obtained for PSS by Kramer and Hoffmann [52] and also high-molecular-weight normal PS, [85] but less than those obtained for PSS by Johner et al [53] The differences between the PSS systems can be explained by the differences in ionic strength between the two polymers used which affects the particle-particle interaction, and therefore the relaxation rates. [53] Assuming a non-free draining bead-spring model values of s = 122-642 ls have been calculated for normal (unfunctionalised) polystyrene in a good solvent for molecular weights of 5.4-15.3) 6 10 6 g N mol -1 , respectively.…”

“…[53,78,79] Although ZT-PS chains are strictly speaking ionomeric the charges are localised at the ends of an otherwise entirely flexible chain. Analysis has therefore been conducted assuming that the chains are fully flexible, where the relaxation dynamics of such molecules in dilute solutions is based on the bead and spring model.…”

“…[53] Assuming a non-free draining bead-spring model values of s = 122-642 ls have been calculated for normal (unfunctionalised) polystyrene in a good solvent for molecular weights of 5.4-15.3) 6 10 6 g N mol -1 , respectively. [85] These values of s are of the same order of magnitude as for the 34.7 6 10 3 ZT-PS.…”

“…[59 -61] For micellar systems this anomalous behaviour has been modelled in terms of a disc-like local clustering of anisometric, polarisable particles. [62] For polyelectrolyte rigid rods, Johner et al [53] and Kramer et al [54] have suggested that the sign of the birefringence and therefore the orientation direction of the rods is a balance between the electrostatic particleparticle interaction and the interaction of a single rod and the electric field. In dilute solutions the particle-particle interaction is negligible so the interaction of a single rod and the electric field dominates producing orientation of the polymers in the direction of the external field, giving a negative sign of the birefringence.…”