1Faculty of Informatics, Teikyo Heisei University, 2289 Uruido, Ichihara, Chiba, 290-0193, Japan
This study explores how propanol affects phase behavior in a complex system with water, a surfactant (C(12)EO(8)), propanol, cyclohexane, and heptane. The researchers found that propanol can act as both a cosurfactant and a cosolvent depending on the oil ratio in the mixture. At certain concentrations, propanol causes the formation of three distinct phases. The presence of the surfactant expands the range of propanol concentrations where this three-phase behavior occurs. The study also identified two types of three-phase regions—closed-loop and chiral. These regions transition into each other through a specific phase region called IIIa. The findings suggest that propanol and the surfactant work together to form higher-order phases. The results may help in designing formulations that require precise control over phase behavior.
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Area of Science:
Background:
Understanding phase behavior in complex liquid mixtures is essential for designing formulations in industries like pharmaceuticals and cosmetics. Prior research has shown that surfactants can influence phase transitions and solubilization. However, the specific role of propanol in systems containing water, surfactants, and hydrocarbons remains unclear. This gap motivated the current study to explore how propanol affects phase separation and dissolution. Existing models do not fully capture the behavior of propanol in such systems. The study addresses this by examining a five-component system with varying ratios. The goal is to clarify how propanol interacts with surfactants and hydrocarbons. This work provides new insights into the mechanisms of phase formation and co-solvent effects. The findings may help optimize formulations requiring precise phase control.
Purpose Of The Study:
The study aimed to investigate how propanol influences phase behavior in a five-component system. The system includes water, C(12)EO(8), propanol, cyclohexane, and heptane. The researchers focused on three-phase regions and dissolution patterns. They tested the system at two temperatures—35 and 45°C. The presence of C(12)EO(8) was a key variable in the experiments. The study also examined how propanol acts as a cosurfactant and cosolvent. The goal was to determine how propanol modifies phase transitions. The findings may help improve the design of surfactant-based formulations.
Propanol modifies phase transitions by acting as a cosurfactant and cosolvent depending on the oil ratio.
C(12)EO(8) expands the three-phase region to propanol concentrations below 20 wt%.
R(oil) determines whether propanol acts as a cosurfactant or cosolvent and influences phase formation.
The D(p) phase forms a closed-loop miscibility gap with the aqueous phase at lower oil ratios.
At higher propanol concentrations, the D phase shifts from water-rich to oil-rich.
Main Methods:
The researchers used a five-component system with controlled ratios. They varied the weight percentages of propanol and the oil ratio (R(oil)). The system was tested at two temperatures—35 and 45°C. Phase behavior was observed using visual inspection and phase diagrams. Three-phase regions were identified based on phase separation patterns. The role of propanol was analyzed in two distinct regimes—R(oil) < 0.2 and R(oil) > 0.3. The study tracked how propanol affected the formation of D(p) and D phases. The experiments included both closed-loop and chiral three-phase regions. The results were compared with and without C(12)EO(8) to assess its influence.
Main Results:
At 35 wt% propanol and R(oil) between 0.2 and 0.3, a three-phase region (IIIa) was observed. Propanol originated from the aqueous phase and became identical to the oil phase at higher R(oil). When C(12)EO(8) was present, the three-phase region expanded to below 20 wt% propanol. At R(oil) < 0.2, a D(p) phase formed a closed-loop miscibility gap with the aqueous phase. Propanol acted as both a cosurfactant and cosolvent in this regime. At R(oil) > 0.3, a microemulsion (D) phase shifted from water-rich to oil-rich. Most propanol acted as a lipophilic cosurfactant at R(oil) = 1. The two types of three-phase behavior were connected via region IIIa.
Conclusions:
The study showed that propanol modifies phase behavior in a five-component system. Propanol acts as a cosurfactant and cosolvent depending on the oil ratio. The presence of C(12)EO(8) expanded the three-phase region to lower propanol concentrations. Two distinct three-phase behaviors were observed—closed-loop and chiral. These behaviors transitioned through region IIIa. The findings suggest that propanol cooperates with C(12)EO(8) to form higher-order phases. The study clarifies how propanol influences phase transitions. The results may help in designing surfactant-based formulations. The authors propose that the system’s behavior depends on the interplay between propanol and C(12)EO(8).
Region IIIa connects two types of three-phase behavior and shows how propanol and C(12)EO(8) interact.