Dilational Viscoelasticity of Polyelectolyte/Surfactant Adsorption Films at the Air/Water Interface:  Dodecyltrimethylammonium Bromide and Sodium Poly(styrenesulfonate)

Abstract

The dynamic surface elasticity of mixed aqueous poly(styrenesulfonate)/alkyltrimethylammonium bromide solutions has been measured by the oscillating barrier, oscillating drop, and capillary wave methods as a function of time and surfactant concentration. At low surfactant concentrations (<0.3 mM) the surface viscoelastic behavior is close to that of relatively concentrated pure PSS solutions. The classical Goddard et al. model cannot explain all the experimental results in this concentration range, and a modification of this model is proposed. At intermediate concentrations the real part of the dynamic surface elasticity drops abruptly by almost 1 order of magnitude. This feature can be connected with the formation of a heterogeneous surface film in accordance with recent results by Monteux et al. (Langmuir 2004, 20, 57). At high surfactant concentration (>2 mM) the modulus of the dynamic surface elasticity is low and the adsorbed film is viscoelastic.

Equilibrium and dynamic aspects of dodecyltrimethylammonium bromide adsorption at the air/water interface in the presence of λ-carrageenan

“…The second step of the adsorption mechanism, the transfer from the subsurface to the surface, associated with another characteristic decay time, τ TR , is not distinguished from the others. The attribution of τ D is corroborated by comparison of the values calculated in this work (350- 650 s) with those estimated by Noskov et al [23], in the order of 500 s, for a similar system, DTAB/poly(styrenesulfonate). Moreover, it is likely that re-orientation of the macro-ion adsorbed together with the surfactant molecules should undergo conformation changes until the equilibrium adsorption is attained, thus affecting the orientation of the DTAB molecules themselves.…”

Adsorption of water-soluble polymers with surfactant character.

“…Surface tension of the aqueous polymer solutions were measured by the Pt-Wilhelmy plate method [24][25][26][27][28], with a commercial Krüss K10 digital tensiometer. Successive readings of the instantaneous surface tension γ (t) were taken at 1 s intervals, after a fresh surface was formed by aspiration of the air-solution interface.…”

Complexes of surfactants with oppositely charged polymers at surfaces and in bulk

“…A maximum in the surface dilatational moduli of about 35 mN m -1 was measured over a narrow range of surfactant concentrations close to C 0 . Noskov et al also studied this system using both the oscillating barrier and the drop method [47]. In the oscillating barrier experiments, the elastic modulus was already large before C 0 , of the order of 90 mN m -1 at 0.1 mM DTAB and 2.4 mM PSS.…”