Structural Evolution of Complexes of Poly(styrenesulfonate) and Cetyltrimethylammonium Chloride

Abstract

Structural evolution is tracked as a charged surfactant, cetyltrimethylammonium chloride (CTAC), is titrated into a solution of oppositely charged polyelectrolyte, sodium poly(styrenesulfonate), to form polyelectrolyte-surfactant complexes. At surfactant-to-polymer molar charge ratio [r] less than 0.5, small-angle neutron scattering of the soluble complexes reveals bound spherical CTAC micelles of radii 21-24 Å, slightly less than for pure CTAC. At such small [r], the number of spherical micelles per chain grows with [r] but never becomes large (<2). At [r] ∼ 0.5, if salt concentration is low (<100 mM), cylindrical micelles of radii 20-22 Å and aspect ratio at least 5:1 replace the spherical micelles. Irrespective of salt concentration, at [r] ∼ 0.7 precipitation occurs, with X-ray scattering revealing CTAC arranged into hexagonally close-packed cylinders. At even higher [r], the hexagonal phase transforms into the Pm3n cubic phase. Raising ionic strength diminishes NaPSS-CTAC attraction, delaying onset of insolubility and disrupting precipitate order.

Effects of the hydrophilicity or hydrophobicity of the neutral block on the structural formation of a block polyelectrolyte/surfactant complex: A molecular dynamics simulation study

“…For instance, the hydrophobic polyelectrolyte chain can penetrate into the micelle and participate in the formation of the micelle in a system containing a polymer chain with a hydrophobic group; in this case, the primitively modeled micelles are too simple to capture the details of this interaction. Recently, we treated the surfactants and homo-polyelectrolytes as chain molecules [7], and the calculated results qualitatively agree with the experimental data [28,29].…”

Electrostatic Control of Structure in Self‐Assembled Membranes

“…The relative positions of the Bragg peaks follow a spacing ratio of 1:√2:√3:√4:√5, which is the characteristic scattering pattern of a cubic phase . This spacing ratio does not fit with Pm3n or Ia3d bicontinuous cubic phases typical for surfactant‐polyelectrolyte complexes . Unfortunately, the exact ordering (e.g.…”

Sulfonation of polystyrene: Toward the “ideal” polyelectrolyte

“…PSS is used as a model polyelectrolyte to probe coil dimensions (especially as a function of salt concentration), electrophoretic mobility, osmotic pressure, and viscosity . Solution structural studies using neutron scattering often employ deuterated PSS . The assumption that PSS prepared in‐house, or supplied commercially, is pure is not always justified.…”

“…8 Solution structural studies using neutron scattering 9 often employ deuterated PSS. 10,11 The assumption that PSS prepared in-house, or supplied commercially, is pure is not always justified. For example, incomplete sulfonation leads to compositional heterogeneity along the backbone and distributions in solution properties.…”