Worm-like soft nanostructures in nonionic systems: principles, properties and application as templates

Area of Science:

• Soft matter science
• Colloid and interface science

Background:

• Worm-like micelles are fascinating soft nanostructured systems formed by nonionic surfactants.
• Their unique properties are crucial for designing viscoelastic networks and advanced materials.

Purpose of the Study:

• To review the principles, occurrence, structure, properties, and characterization methods of worm-like micellar solutions.
• To explore the influence of formulation, temperature, and additives on these systems.

Main Methods:

• Review of experimental methods for characterizing soft nanostructured systems.
• Analysis of formulation effects, including cosurfactants and oils.
• Investigation of temperature effects and salt interactions.

Main Results:

• Micellar growth is favored by increased surfactant molecular packing parameter, tunable via cosurfactants or oils.
• Longer, bulkier oils induce a rod-sphere transition, decreasing viscosity.
• Temperature effects involve a balance of head group dehydration and micellar disruption, often leading to a viscosity maximum.
• Nonionic worm-like micelles show minimal response to salts, unlike ionic systems.
• Reverse worm-like micelles can form in organic solvents.
• Worm-like micelles serve as templates for ordered mesoporous oxides via silica-surfactant complexation.

Conclusions:

• Formulation is key to controlling worm-like micellar systems and their viscoelastic properties.
• Understanding the interplay of formulation, temperature, and additives is essential for their application.
• Worm-like micelles offer a versatile platform for materials synthesis, particularly for mesoporous oxides.