Nanostructured fluids based on propylene carbonate/water mixtures

Area of Science:

• Colloid and Surface Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Understanding the self-assembly of surfactants is crucial for designing novel materials.
• Propylene carbonate (PC) is a polar aprotic solvent with potential applications in complex fluid systems.
• The role of cosurfactants in modifying micellar structures and properties requires detailed investigation.

Purpose of the Study:

• To elucidate the microstructure of aggregates formed by sodium dodecyl sulfate (SDS), 1-pentanol, and propylene carbonate (PC) in aqueous mixtures.
• To investigate the partitioning behavior of PC within the aggregate structures.
• To characterize the influence of PC on interfacial area and aggregate size.

Main Methods:

• Pulsed gradient spin-echo Nuclear Magnetic Resonance (NMR) spectroscopy.
• Dynamic Light Scattering (DLS).
• Viscosity and conductivity measurements.

Main Results:

• Propylene carbonate (PC) partitions between the micellar palisade layer and the aqueous bulk, acting as a cosurfactant.
• Phase separation occurs at the PC/water miscibility gap.
• At high PC content, very small aggregates (approx. 10 Å radius) composed of SDS, PC, and pentanol are formed.
• These systems exhibit a nanostructured fluid behavior with a large interfacial area.

Conclusions:

• PC significantly increases the interfacial area in SDS/pentanol/water systems, functioning as an effective cosurfactant.
• The addition of PC leads to the formation of unique nanostructured fluids with potential applications.
• The observed microstructures are dependent on the concentration and miscibility of the components.