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Heat capacity, conductivity, and structural changes of water-sodium dodecylsulfate-triethanolamine-1-pentanol-1,1,2,2-tetrafluorodibromoethane microemulsions

“…In order to obtain additional data on the structure of microemulsions the concentration and temperature dependences of their specific conductivity and specific isobaric heat capacity were determined. The conductivity is most often used to study the structural changes in surfactant micellar solutions and microemulsions [18,19], e.g., to find the critical concentration of surfactant micellization [20], the percolation threshold in w/o type microemulsions [18,[21][22][23][24]. It should be noted that apart from the conductivity, a change in the structure of microemulsions is usually accompanied by an abrupt change in viscosity [17,18,23], some bulk properties, the temperature coefficient of the internal pressure [24][25][26], and optical [27] properties of the microemulsions.…”

Precision Dilatometry of Microemulsions with Anionic Surfactants

“…Their composition is shown in Table 1. The selection of just these microemulsions is due to the fact that their structure has been extensively studied by various methods [3,[18][19][20][21] and thus it was easier to interpret our results. All the microemulsions remained macroscopically single-phase and transparent in the studied concentration range at 15 and 25°ë.…”

“…(2), one needs to know their isothermal compressibility β í and thermal expansion coefficient α. Measurements of β í and α were performed using a unique dilatometer [17], which measured the density ρ of the microemulsions simultaneously with β í and α. The method and technique of the experiment are described in [17]; some of its special features related to studies of microemulsion systems are discussed in [18]. The measurement errors amounted to 5 × 10 -3 % for ρ, to 1% for β í at pressure drop ∆ê ~4 × 10 5 Pa, and to 2% for α at temperature drop ∆í ~ 0.4°ë.…”

“…Conductometric, viscometric, and fluorometric studies of the selected microemulsion series show that it includes two types of microemulsions (w/o and o/w) and a bicontinuous phase [18][19][20]. This implies that phase inversion takes place in the microemulsion series as the water/oil ratio changes.…”

Reichardt betaines as combined solvatochromic and acid-base indicators in microemulsions

“…Microdroplets can be larger in size by an order of magnitude than surfactant micelles [15,16], being of tens nanometers. Taking into account the occurrence of a hydrocarbon core inside the droplets, this causes stronger inhomogeneity of the dispersed phase (called pseudophase or microphase) than in the case of surfactant micelles.…”