Structurally Stable Attractive Nanoscale Emulsions with Dipole-Dipole Interaction-Driven Interdrop Percolation.

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Nanotechnology

Background:

• Amphiphilic block copolymers are crucial for stabilizing interfaces.
• Lecithin, a natural phospholipid, plays a key role in biological membranes and emulsions.
• Developing stable nanoemulsions with enhanced properties is essential for various applications, including drug delivery.

Purpose of the Study:

• To introduce an extremely stable attractive nanoscale emulsion fluid.
• To investigate the role of poly(ethylene oxide)-block-poly(ϵ-caprolactone) (PEO-b-PCL) and lecithin in forming a robust interface.
• To evaluate the nanoemulsion's potential for enhanced transdermal delivery.

Main Methods:

• Utilizing amphiphilic block copolymers (PEO-b-PCL) and lecithin to form a thin-film at the oil-water interface.
• Employing T₂ relaxation and Differential Scanning Calorimetry (DSC) to analyze molecular assembly.
• Conducting suspension rheology studies to assess interdroplet attractions and network formation.
• Evaluating transdermal delivery efficiency and skin interaction.

Main Results:

• A mechanically robust thin-film was formed at the oil-water interface due to tight packing of PEO-b-PCL and lecithin.
• Molecular association confirmed by T₂ relaxation and DSC, indicating a denser interfacial assembly.
• Rheology studies revealed interdroplet attractions and a percolated network, preventing coalescence and phase separation.
• Dipolar interactions between lecithin and PEO-b-PCL were identified as the cause of unique rheological behavior.

Conclusions:

• The developed nanoemulsion exhibits exceptional stability and attractive properties.
• The synergistic interaction between PEO-b-PCL and lecithin is key to the nanoemulsion's robustness.
• The nanoemulsion system demonstrates significant potential for enhancing transdermal delivery due to favorable skin attraction and high drop diffusivity.