Aggregation Model That Describes the Physical Properties of the Sodium Dodecyl Sulfate/Poly(propylene glycol) System in Aqueous Solution

Abstract

Micellar ionization degrees, from conductivity measurements, and micellar aggregation numbers, from steady-state quenching fluorescence of the sodium dodecyl sulfate/poly(propylene glycol) (SDS/PPG) (MW ) 425 and 1000) systems in aqueous solution, have been obtained. From the experimental results we conclude that small aggregates form on the polymer chain at a surfactant concentration c 1 smaller than the surfactant cmc. The aggregation numbers of these aggregates sharply increase with SDS concentration and, at a critical surfactant concentration (c2) higher than the SDS cmc, the aggregates become large enough to incorporate the polymer chains into the surfactant micelles, forming SDS/PPG mixed micelles in aqueous solution, that are similar to the cetyltrimethylammonium bromide (CTAB)/PPG and surfactant/ medium chain alcohols mixed micelles.

Aqueous Solutions of Sodium Deoxycholate and Hydroxypropylmethylcellulose: Dynamic Surface Tension Measurements

“…The formation of these associates is assumed to take place at a surfactant concentration well below the cmc, the critical aggregation concentration (cac). On increasing the surfactant concentration, the polymer chain becomes saturated with surfactant aggregates and above this concentration simple surfactant micelles are formed in the aqueous solution, in equilibrium with the polymer surfactant complexes (32,33). The addition of DOC concentrations above 2 × 10 −4 M, i.e., above cac, in the two low concentrations of the polymer solution results in a change in the adsorption kinetics.…”

Autoassociação de misturas dos Surfactantes Dodecanoato de Sódio (SDoD) e Decanoato de Sódio (SDeC) com o Polímero Hidrofobicamente Modificado Etil(Hidroxietil)Celulose (EHEC)

“…30 acordo com a interpretação clássica dada a este perfil. 10,21,[33][34][35][36] As Figuras 2 e 3 mostram os perfis de condutividade elétrica de três misturas de SDoD e SDeC com composições diferentes, em presença de 0,1 e 0,2% (m/v) de EHEC, respectivamente.…”

Auto-associação do dodecilsulfato de sódio (SDS) com o polímero hidrofobicamente modificado etil(hidroxietil) celulose (EHEC)

“…26,37 O psp, que na Figura 2 ocorre em 26 mM de SDS, representa a concentração na qual ocorre a saturação das cadeias do polímero EHEC por monômeros de SDS. 26,38 Em concentrações acima do psp, os valores de tensão superficial (g 2 ) quando na ausência e em presença de EHEC são semelhantes (Tabela 1). Este fato é forte indicação de que, acima do psp, todo SDS adicionado forma micelas livres que estão em equilíbrio com o complexo EHEC-SDS.…”

“…38,44,45 De outro lado, o grau de ionização dos complexos EHEC-SDS (α 2 ), pode ser estimado a partir da razão S 2 / S 1…”