Ordered Nonstoichiometric Polymer Gel−Surfactant Complexes in Aqueous Medium with High Ionic Strength

• Published in: Macromolecules 1998-11, Vol.31 (22), p.7698-7705
• Main Authors: Mironov, A. V, Starodoubtsev, S. G, Khokhlov, A. R, Dembo, A. T, Yakunin, A. N
• Format: Article
• Language: English
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma971816w

The effect sodium chloride on the composition and structure of network polymer−surfactant complexes (NPSC) formed by slightly cross-linked networks of poly(diallyldimethylammonium chloride) (PDADMACL) and oppositely charged surfactants of sodium dodecylbenzenesulfonate (SDBS) was studied. The comparison of the composition of NPSC with the data obtained by SAXS shows that, at some content of the surfactant ions in the gel phase, highly ordered lamellar structure in NPSC is formed. In the solution of high ionic strength and at significant excess of the surfactant molecules in the external solution, this highly ordered NPSC can be strongly nonstoichiometric. The excess of the surfactant anions in the polyelectrolyte network first increases with the increase of the ionic strength of the solution, reaching a maximum at c = 0.3 M NaCl, and only after that starts to decrease. The degree of spatial order in NPSC becomes more pronounced when the nonstoichiometric complexes in the solution of high ionic strength are formed. These results are explained by introducing the model in which the fitting of packing of the surfactant and polymer components in NPSC is improved by the inclusion of extra surfactant molecules together with their counterions in the highly ordered structure.