Microemulsions Based on Diverse Surfactant Molecular Structure: Comparative Analysis and Mechanistic Study

Abstract

Microemulsion flooding technology, known for significantly reducing interfacial tension, improving rock wettability, and providing strong driving forces at the microscopic level, has been widely applied in enhancing oil recovery in oil fields. This article summarizes the relevant literature and introduces the classification, formation mechanisms, research models, and factors affecting the performance of microemulsions. Particularly, it conducts a comparative analysis of microemulsion systems formed by surfactant molecules of different structures, aiming to provide new perspectives for the study of surfactant molecular structures and to further optimize the performance of microemulsion systems. The study finds that modifying surfactant molecules by adding benzene rings, increasing the length of hydrophobic tails, and enlarging hydrophilic heads can significantly increase the volume of the middle phase, exceeding 30%. These findings provide important guidance for optimizing microemulsion systems.

Strategies to Improve the Transdermal Delivery of Poorly Water-Soluble Non-Steroidal Anti-Inflammatory Drugs

“…Alternative theories, such as hydrophilic-lipophilic deviation (HLD), that incorporate formulation salinity and temperature may also be used to inform surfactant selection and the optimal conditions for ME formation [233][234][235]. Additionally, the packing parameter (PP) theory is often used to estimate the curvature of the interfacial film based on the geometry of the surfactant molecules and packing at the oil-water interface, and can be explained by the following equation [236].…”

“…Following this theory, when PP < 1, a positive curvature is created and O/W MEs are created, with the opposite being true for PP > 1. When PP = 1, a neutral curvature is produced, giving rise to bicontinuous or liquid crystalline structures [236]. However, this overly simplified system is also limited in predicting the microstructure in these systems with complex interactions and with changes in temperature.…”

Advancements in Characterization Techniques for Microemulsions: From Molecular Insights to Macroscopic Phenomena

“…Conversely, when R > 1, the interaction force between the interface and the water phase is stronger, causing the interface to bend toward the oil phase and making it easier to form a W/Otype microemulsion. The diverse molecular interaction energies across different molecular types [26].…”