Aggregation and Adsorption at the Air–Solution Interface of the Cetyltrimethyl Ammonium Tosylate With Two Poly(oxyethylene)–Poly(oxypropylene)–Poly(oxyethylene) Block Copolymers Aqueous Mixtures

Abstract

The aqueous mixed systems (EO 76 PO 30 EO 76 ) (TBCP8400)-cetyltrimethyl ammonium tosylate (CTAT), and (EO 97 PO 69 EO 97 ) (TBCP12600)-CTAT were studied to determine both the bulk aggregation and the adsorbed monolayer at the air/water interface. Results were interpreted with the pseudophase separation model plus the regular solution theory for aggregates and monolayers. The behavior is different for TBCP8400-CTAT and TBCP12600-CTAT mixtures, but it is strongly non-ideal in both cases. In bulk, TBCP8400-CTAT mixtures produce aggregates more close to CTAT micelles having TBCP8400 as a solubilizate than the inverse. At low CTAT content, the interaction is repulsive becoming attractive at high TBCP8400 content. The TBCP12600-CTAT aggregates strongly differ from the structure of both pure component micelles, and the interaction is always repulsive. In both cases, the interaction seems not to be cooperative but gradual. CTAT effect on copolymers aggregates seems to be more similar to that of a zwitterionic surfactant than to that of an ionic one. However, CTAT is not included in the aggregates as an ion pair, as revealed by the ionization degree results. It seems that cetyltrimethyl ammonium and tosylate ions have different effects on aggregates which in part are opposite. The adsorbed monolayers also show different behavior. In TBCP8400-CTAT system, the monolayer is mainly a CTAT one with inclusion of TBCP8400 as a monolayer-soluble impurity. However, the inclusion of the non-ionic surfactant alters the structure of the monolayer, which differs from that of the pure CTAT one. The area per adsorbed molecule (A 0 ) is systematically higher than the ideal and computed ones. The system TBCP12600-CTAT shows a monolayer composition which is almost the same that the overall surfactant mixture composition, and the monolayer structure differs from both the pure-TBCP12600 and the pure-CTAT monolayers ones. The experimental A 0 values are systematically lower than the ideal and the computed ones. Then, in both cases the A 0 values for the pure components do not remain invariable in the mixed monolayer. The phenomenon is interpreted on the basis of the conformation of the copolymers adsorbed at the air/solution interface.

Investigation of mixed ionic/nonionic building blocks for the dual templating of macro-mesoporous silica

“…However, since it is well known that non-ionic and ionic surfactants can interact to form mixed-systems with properties that cannot be found in individual surfactant [39][40][41][42][43], prior to the preparation of the hierarchical materials, we have investigated in detail the TTAB/P123/water system. The effect of dodecane solubilization has also been considered, since this oil is used to formulate the concentrated emulsions.…”

Interaction between Cetyltrimetylammonium Tosylate and Two Poly(oxyethylene)–Poly(oxypropylene)–Poly(oxyethylene) Block Copolymers Studied by Cyclic Voltammetry

“…To compute κ –1 we used the KCl concentration as the ionic strength, because the CAC values are an order of magnitude smaller, and only the CTAT component is ionic. To compute the value of V M the volume of the equivalent surfactant molecule ( V s ) was calculated as: V normals = V CTAT x CTAT + V Pluronic x Pluronic where x CTAT and x Pluronic are the mole fraction of the components in micelles (taken from a previous work); the volumes of the components ( V CTAT and V Pluronic ) were computed from the partial molar volumes (PMV) of CTAT and Pluronics F127 and F68 in the micellar state. The partial molar volume of CTAB is PMV CTAB = 365.4 cm 3 ·mol –1 , which by subtraction of the PMV of Br – (29.2 cm 3 ·mol –1 ) gives a value for PMV CTA + of 336.2 cm 3 ·mol –1 .…”

“…In our previous work, we found that the interaction between CTAT and F68 is different from that observed between CTAT and F127 . To obtain more information about the nature of these interactions, in this work we have determined the aggregates’ diffusion coefficient, which is related with the aggregates’ size and shape.…”

“…In a previous work we studied the critical aggregation concentration of mixtures consisting of two poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) block copolymers, known as poloxamers or Pluronics, with hexadecyltrimethylammonium p -toluene sulfonate (cetyltrimetylammonium tosylate, CTAT). The Pluronics used for these studies were F127 (PEO 97 PPO 69 PEO 97 ) and F68 (PEO 76 PPO 30 PEO 76 ).…”

Surface modification of HSA containing magnetic PLGA nanoparticles by poloxamer to decrease plasma protein adsorption

“…Poloxamers are triblock copolymers having PPO (polypropyleneoxide) and PEO (polyethyleneoxide) blocks [9,10]. They can interact with hydrophobic particles, biological membranes, etc [11][12][13]. The structure of poloxamer and their adsorption pattern onto hydrophobic PLGA NPs are shown in Figure 1.…”