Responsive Pickering Emulsions Stabilized by Frozen Complex Coacervate Core Micelles

Area of Science:

• Polymer Science
• Colloid and Surface Science
• Materials Science

Background:

• Pickering emulsions are stabilized by solid particles.
• Conventional stabilizers like block copolymers can be unstable at interfaces.
• Novel particle stabilizers are needed for advanced emulsion applications.

Purpose of the Study:

• To develop and characterize frozen complex coacervate core micelles (C3Ms) as particle stabilizers for Pickering emulsions.
• To investigate the stability and disassembly mechanism of C3Ms under varying conditions.
• To evaluate the performance of C3Ms in stabilizing dodecane-in-water emulsions.

Main Methods:

• Synthesis of C3Ms by mixing poly(acrylic acid) (pAA) and poly(dimethylaminopropylacrylamide) (pDMAPAA) with a poly(N-isopropylacrylamide) (pNiPAM) corona.
• Characterization using dynamic light scattering (DLS) and proton nuclear magnetic resonance (1H NMR).
• Formulation and stability testing of dodecane-in-water emulsions with C3Ms at varying NaCl concentrations.

Main Results:

• Monodisperse and colloidally stable C3Ms were successfully synthesized by controlling mixing parameters (pH, mixing method, charge ratio, salinity).
• C3Ms demonstrated gradual disassembly into free polyelectrolyte chains above 0.8 M NaCl.
• C3Ms adsorbed effectively as particles at dodecane-in-water emulsion interfaces, unlike conventional micelles.
• High salt concentrations triggered C3M disassembly, leading to emulsion destabilization.

Conclusions:

• Frozen complex coacervate core micelles (C3Ms) are effective particle stabilizers for Pickering emulsions.
• The salt-induced disassembly of C3Ms provides a mechanism for controlled emulsion destabilization.
• C3Ms offer a tunable alternative to conventional stabilizers in emulsion technology.