Pair Potential between Poloxamer 407 Micelles in 14 wt % Aqueous Solution Clarifying the Sol-Gel-Sol Transition by...

Area of Science:

• Colloid and Surface Chemistry
• Materials Science
• Physical Chemistry

Background:

• Poloxamer 407 (P407) is a widely used pharmaceutical nanocarrier.
• P407 aqueous solutions exhibit temperature-dependent sol-to-gel and gel-to-sol transitions.
• Understanding the micellar interactions is crucial for controlling P407 behavior.

Purpose of the Study:

• To develop a method for determining pair potentials between colloidal particles.
• To elucidate the intermicellar pair potential of P407 during sol-gel-sol transitions.
• To identify the key factors governing P407 gelation and phase transitions.

Main Methods:

• Utilized experimental small-angle scattering data.
• Developed a novel approach to determine pair potentials without pre-limiting interaction types.
• Applied Alder transition theory to analyze the fluid-to-crystal phase transition.

Main Results:

• Revealed the pair potential between P407 micelles in the sol-gel-sol transition state.
• Demonstrated that increased attractive interactions enhance volume fraction, driving gelation.
• Identified enhanced structural fluctuations due to potential well widening as a mechanism for gel-to-sol transition.

Conclusions:

• The study provides a method to determine interparticle potentials from scattering data.
• Attractive interactions and volume fraction are key to P407 gelation.
• Structural fluctuations explain the heating-induced gel-to-sol transition in P407 systems.