Phase Diagram and Structures in Mixtures of Poly(styrenesulfonate anion) and Alkyltrimethylammonium Cations in Water: Significance of Specific Hydrophobic Interaction

Abstract

Mixtures of polyelectrolytes and oppositely charged surfactants show very rich phase behavior that is influenced by surfactant-ion and polyion properties and by water content. A general feature is associative phase separation as a result of strong electrostatic interactions, whereas the effect of eventual more specific interactions (e.g., hydrophobic) has not been thoroughly investigated. In this paper, we report a detailed study on phase behavior and structures in poly(styrenesulfonate anion) (PSS(-))-cetyltrimethylammonium cation (CTA(+))-water mixtures that are characterized by a hydrophobic interaction between the styrene groups of PSS(-) and the micelle interior. Structures of various phases were determined by small-angle X-ray scattering, and results indicated the presence of a disordered micellar and an ordered hexagonal phase; no cubic phase was found. The general conclusion is that the highlighted hydrophobic interaction promotes dissolution of CTAPSS when the polyion salt is added and provides further stabilization of the dense phase when the surfactant salt is added.

Complexation between Sodium Poly(styrenesulfonate) and Alkyltrimethylammonium Bromides in the Presence of Dodecyl Maltoside

“…19−22 Some studies revealed that the PSS/C n TAB complexation is driven not only by the electrostatic and hydrophobic interactions related to the headgroup and tails of the cationic amphiphiles, but also by the specific interactions that originated from the penetration of the aromatic groups of the PSS into the polyanion/cationic surfactant complexes. 17,30 The orders of magnitude lower critical aggregation concentration of the cationic surfactants on PSS compared to their cmc was also rationalized with this structure. 23 In the presence of 0.1 mM dodecyl maltoside, the micropolarity of the pyrene probe changes similarly with the The Journal of Physical Chemistry B Article cationic surfactant concentration as in the case of the nonionic amphiphile-free mixtures.…”

Polyelectrolyte/surfactant films spread from neutral aggregates

“…Note that while the internal structure of the NaPSS/DTAB aggregates was not investigated in the present work, Sitar et al presented data on the phase diagram of the PSSDTA/water system and found that above 43% water content coexisting hexagonal ('precipitate') and micellar ('dilute') phases form. 44 We begin our focus on the interfacial properties by examining how the dissociation of neutral P/S aggregates can be used to create spread films. Thus, we spread a small aliquot (100 mL) of a freshly prepared mixture containing neutral aggregates (100 ppm NaPSS and 6 mM DTAB) on 25 mL of pure water using a pipette.…”

Binding of Lysozyme to Spherical Poly(styrenesulfonate) Gels

“…In the present paper we investigate this further by studying the binding of lysozyme to sodium poly(styrenesulfonate) (PSS) microgel spheres by means of micropipette-assisted microscopy. PSS is known to interact electrostatically and hydrophobically with lysozyme [39,40,41] and with cationic surfactant micelles [42,43,44,45], in contrast to PA which is expected to display mainly electrostatic interactions. One motive behind the study is thus to investigate how the hydrophobic backbone of PSS affects the binding and aggregation of lysozyme in gels.…”