Vinyltoluene–Styrene Copolymer Sulfonic Acids. II. Ionic Dissociation in Methanol–Water and HCl–Water Solutions

Abstract

Vinyltoluene-styrene copolymer sulfonic acids in dilute solution exhibit conductance behavior which differs appreciably from that of strong 1:1 electrolytes and other chain polyelectrolytes. The equivalent conductance of the polysulfonic acid shows no observable dependence on either polymer concentration or total solution ionic strength at moderate to very high dilutions. However, sodium poly-p-etyrenesulfonate shows a variation of equivalent conductance with concentration which is functionally identical to behavior observed by other workers for sodium polymethacrylate and poly-4-vinyl-N-n-butylpyridinium bromide. Proton counterions are apparently the major contributors to polysulfonic acid solution conductance, which does not vary greatly with polymer molecular weight. Values of ionic dissociation in methanol-water systems were calculated under the assumption of negligible polysulfonate ion mobility. In the regions 0-60% and 90-100% methanol the dissociation is apparently proportional to the solvent dielectric constant. Elsewhere, the dissociation of the polyacid is not significantly influenced by the methanol content of the solvent.

Optical Properties of Polyelectrolytes

“…A measure of success was achieved in description of the data, however, through use of the Hindered Access Model [1] (see Equation 2.13). The data were also consistent with an extended PSS conformation in the presence of low concentrations of salt, which is in agreement with other fluorescence data [87,145,150] and light scattering and viscosity measurements [136][137][138][139] Potentiometric [50] and viscometric [151] measurements on poly [2-(dimethylamino) ethyl methacrylate] (PDMAEMA) indicate that the polyelectrolyte undergoes a conformational change from an expanded structure at low pH when the amine unit is fully protonated, to a collapsed structure at high pH. The data were also consistent with an extended PSS conformation in the presence of low concentrations of salt, which is in agreement with other fluorescence data [87,145,150] and light scattering and viscosity measurements [136][137][138][139] Potentiometric [50] and viscometric [151] measurements on poly [2-(dimethylamino) ethyl methacrylate] (PDMAEMA) indicate that the polyelectrolyte undergoes a conformational change from an expanded structure at low pH when the amine unit is fully protonated, to a collapsed structure at high pH.…”

“…This contrasts to the behavior observed for a similarly labeled PMAA [87], which could only be modeled through use of a double-exponential function of the form of Equation 2.7. The fact that only one excited state species is present in the PSS sample is indicative that the coil is more homogeneous in nature which is consistent with an extended conformation [136][137][138][139] under salt-free conditions. The fact that only one excited state species is present in the PSS sample is indicative that the coil is more homogeneous in nature which is consistent with an extended conformation [136][137][138][139] under salt-free conditions.…”

“…However, the degree of water penetration and expansion in this conformation is such that PAA is unable to solubilize probes [17] or certainly presents the low molar mass material with a microenvironment very similar to that of the aqueous phase [20]. Viscosity and light scattering measurements [136][137][138][139] indicate that PSS exists in an extended conformation at all pH values but forms a compact coil under high salt concentrations. Viscosity and light scattering measurements [136][137][138][139] indicate that PSS exists in an extended conformation at all pH values but forms a compact coil under high salt concentrations.…”

Oligo(ethylene oxide) side‐chain steric screening effects on conductimetric properties of grafted poly(4‐vinylpyridinium) salts in aqueous solutions

“…Conductimetry is an important tool to investigate physicochemical properties of electrolyte solutions because it measures the mobility of the charged species and the evaluation of interactions that reduce this mobility 17–24. Polyelectrolytes are particularly interesting examples of electrolytes, since the counter‐ions can be considered more or less bound to the polyion which exhibits a strong local charge along its skeleton.…”

“…Even if there is a lack of an adequate theory considering all types of interactions, these measurements allow at least a qualitative estimate of the polyion–counterion interactions. Conductivity measurements for many polyelectrolyte systems have been reported, but only a few studies on concentration effects over an extended concentration range can be found 17–29. Moreover, most of these studies have been carried out on anionic polyelectrolytes 18, 21, 24–33.…”