Molecular interaction in binary surfactant mixtures containing alkyl polyglycoside

Surface tension for the binary mixtures of a biosurfactant sodium deoxycholate (NaDC) with three different conventional surfactants (p-(1,1,3,3-tetramethylbutyl)phenol polyoxyethylene, polyoxethylene-10-oleyl ether, and sodium oleate) were measured in buffer solutions at different temperatures. Surface properties were determined as well as the micellar characteristics like composition, micellar molecular interaction parameter (b), activity coefficients (f 1 , f 2 ), and the free energy of micellization were analyzed using some theoretical models, including Clint, Rubingh, Motomura and Maeda models. The results reveal that all the three investigated systems show non-ideality in the micelle formation by the deviation in the experimental critical micelle concentration (CMC), f 1 , f 2 , and negative b values from the ideal values. The proportion of NaDC in the mixed micelle (X 1 ) calculated by all models increases with increasing the molar fraction of NaDC in solution (a NaDC ), but the X 1 values are very small even at the high a NaDC . Moreover, by using the Maeda theory, the results suggest the chain-chain interaction among surfactants does not seem to be strong. It is noted that two break points were observed in the surface tension plots of pure NaOL and NaDC/NaOL mixture solutions. Interestingly, by introducing moderate NaDC or decreasing the temperature, the first break point disappeared for the two systems.

Section: Resultsmentioning

confidence: 99%

Surface Properties and Micellar Molecular Interaction in Binary Systems of a Biosurfactant Sodium Deoxycholate (NaDC) with Conventional Surfactants

Wang

et al. 2010

“…where e and e m are the molecule exchange energy in mixed monolayer and mixed micelle and g p is a parameter calculated on the assumption that surfactant 1 and surfactant 2 are packed in a optimum way in both monolayer and micelle [28,29]. The difference between e and e m for a given surfactant mixture is a measurement of the relative ability of the mixture to form mixed monolayers or to form mixed micelles.…”

Section: Critical Micelle Concentrationmentioning

confidence: 99%

The Properties of Binary Mixtures of Ethoxylated Octyl Phenols with Ethoxylated Fluorinated Alkanols at the Water/Air Interface

Szymczyk

2011

Surface tension measurements were carried out for systems containing binary mixtures of ethoxylated tertoctylphenols (with an average of 10 or 16 ethylene oxide groups-HC8PEO10 and HC8PEO16, respectively) with perfluorinated n-alcohol ethoxylates (fluoropentanol with an average of 10 ethylene oxide groups FC5EO10, and fluorohexanol with an average of 14 ethylene oxide groups FC6EO14). The obtained results and calculations indicate that fluorinated surfactants have the better efficiency and effectiveness in the reduction of surface tension of water that the hydrocarbonated alkyl phenol ethoxylates and that their mole fraction in the mixed monolayer at water-air interface for mixtures containing a 0.2 molar fraction of fluorinated surfactants in bulk phase is considerable higher than in the bulk phase. At concentrations of mixtures corresponding to saturated monolayer at water-air interface there is a synergetic effect in the reduction of c LV for a mixture of HC8PEO16 ? FC5EO10 at a 0.2 molar fraction of HC8PEO16; however, taking into account the lowest value of the molecular interaction parameter for mixed micelles calculated on the basis of Rosen approach, the result is that the best synergism takes place for mixture of HC8PEO16 ? FC6EO14 at a 0.2 molar fraction of HC8PEO16. Moreover, the ability of the mixed monolayer formation relative to the mixed micelle formation varies with the concentration and composition of the studied mixtures.

“…R = 8.314 J/(mol K), and N is Avogadro's number. Assuming surfactant 1 and surfactant 2 are packed in an optimum way in both monolayer and micelle, the value of g is taken as 6 in this case [18]. The interaction parameter (b r and b M ) and the exchange energy (e and e m ) represent the deviation of the mixture from ideal behavior.…”

Section: Surfactant-surfactant Interactionmentioning

confidence: 99%

Interactions Between an Anionic Fluorosurfactant and a PEO‐PPO‐PEO Triblock Copolymer in Aqueous Solutions

Wang

2009

Surface tensions were determined for a mixture of an anionic fluorinated surfactant and a PEO-PPO-PEO triblock copolymer. The interactions between the two surfactant molecules in the mixed monolayer and the mixed micelle were studied through molecular interaction parameters (b r , b M ) and the molecule exchange energy (e, e m ). It was noted that synergism and strong attractive interactions took place between the anionic fluorinated surfactant and the triblock copolymer molecules in both mixed micelles and mixed monolayers, reflected by the interaction parameter values of between -10 and -18 for all mixtures investigated. Moreover, it can be seen from the value of (e -e m ) that when the mixture has a small amount of triblock copolymer, the formation of mixed micelle results in a greater decrease in energy than does the formation of a mixed monolayer. With an increase in the mole fraction of the triblock copolymer in the mixture, in order to obtain the lowest surface energy, surfactants tend to form mixed monolayers first, and then form mixed micelles.