Osmotic coefficients of aqueous polyelectrolyte solutions at low concentrations, 1. Polystyrenesulfonates with mono‐ and bivalent counterions

Abstract

With the aid of a membrane osmometer, the osmotic coefficients, @, of aqueous solutions of polystyrenesulfonic acid and its salts with mono-and bivalent counterions were measured at molalities from 1.10-to less than 1.10-mol/kg. The results were inconsistent with published "limiting laws" and a dependence of @ on the nominal molecular weight of the macroions was observed. The obtained @-values were compared with the data compiled from other studies. The @-values for solutions containing H and Ca counterions were compared with the corresponding @-values obtained cryoscopically to establish the validity of the method used. ZUSAMMENFASSUNG:Mit einem Membranosmometer wurden die osmotischen Koeffizienten (@) waBriger Losungen von Polystyrolsulfonsaure und ihrer Salze mit mono-und divalenten Gegenionen im Konzentrationsbereich von 1.10-bis 1.10-mol/kg und niedriger gemessen. Es wurde keine Ubereinstimmung der Resultate rnit "limiting laws" aus der Literatur gefunden, und es wurde eine Abhangigkeit der osmotischen Koeffizienten von den nominalen Molekulargewichten der Makroionen beobachtet. Die erhaltenen @-Werte wurden mit den aus anderen Arbeiten entnommenen Ergebnissen verglichen. Die @-Werte von Losungen, die H und Ca Gegenionen enthielten, wurden rnit den entsprechenden @-Werten aus kryoskopischen Messungen verglichen, um die Gultigkeit der benutzten Methode zu bestatigen.

Molecular Dynamics Simulations of Polyelectrolyte Solutions: Osmotic Coefficient and Counterion Condensation

“…The osmotic pressure of polyelectrolytes in salt-free solutions exceeds the osmotic pressure of neutral polymers at similar polymer concentrations by several orders of magnitude. [1][2][3][4][5][6][7][8][9] It increases almost linearly with polymer concentration and is independent of the chain molecular weight in a wide range of polymer and salt concentrations. [1][2][3][4][5][6][7][8][9] This almost linear concentration dependence of the osmotic pressure is due to the contribution from counterions.…”

High-Performance Filaments from Fractionated Alginate by Polyvalent Cross-Linking: A Theoretical and Practical Approach

“…The exception is alginate with a high M-to-G ratio, which has a lower tendency to form aggregates and where the effective degree of ionization thus can be more accurately determined. Measurements of the effective degree of ionization on an M-rich alginate resulted in a value of i = 0.28 for normal to high molecular weight alginate, , while alginate with a higher share of G was estimated to have i = 0.30. , Both M and G in alginate have a charge distance below that of the Bjerum length ( l B , 7.1 Å at room temperature), which is the limit where, theoretically, a decrease in charge distance has a low impact on the effective degree of ionization. ,, It has also been shown that the polymer concentration and reasonable excess concentration of divalent salt only have a low impact on effective degree of ionization. ,− We found that an effective degree of ionization of i = 0.30 fitted best to the empirical data, which is reasonable because it is close to the literature values of alginate. It is important to note that this fit concerns a gel with a compositional ratio of 50% GG dyads.…”

Thermodynamic study of aqueous solutions of polyelectrolytes of low and medium charge density without added salt by direct measurement of osmotic pressure

“…Data obtained were in the same range as has been found earlier in the literature for other types of polyelectrolytes (cf. references [42][43][44][45]). However, there were two interesting new observations: first, the samples studied formed two separate groups as a function of ADDG; second, the initial sections of all curves had very large slopes followed by a function of ''saturation" type.…”