Dynamic Covalent Nanoparticles for Acid-Responsive Nonaqueous Pickering Emulsions

Area of Science:

• Colloid and Surface Science
• Materials Chemistry
• Nanotechnology

Background:

• Pickering emulsions offer an alternative to conventional emulsions, utilizing solid particles for stabilization.
• Nonaqueous Pickering emulsions are crucial for applications involving water-sensitive materials.
• Developing responsive Pickering emulsions with tunable properties remains an active research area.

Purpose of the Study:

• To synthesize and characterize acid-responsive, oil-wetted Pickering emulsifiers.
• To prepare and investigate the stability of nonaqueous Pickering emulsions using these emulsifiers.
• To demonstrate the controlled phase separation of these emulsions in response to acidic conditions.

Main Methods:

• Synthesis of acid-responsive silica nanoparticles (SiO2-pDB) via Schiff base reaction.
• Characterization of nanoparticle formation using FTIR, TGA, and elemental analysis.
• Preparation and stability testing of nonaqueous Pickering emulsions in glycerol/n-decane systems.
• Evaluation of emulsion response to acidic pH changes.

Main Results:

• Successfully synthesized preferentially oil-wetted SiO2-pDB nanoparticles.
• Prepared stable nonaqueous Pickering emulsions using SiO2-pDB.
• Observed complete phase separation of emulsions upon exposure to acidic conditions.
• Confirmed decomposition of SiO2-pDB into hydrophilic SiO2-NH2 and hydrophobic pDBA in acid.

Conclusions:

• Acid-triggered decomposition of dynamic covalent nanoparticles enables controlled emulsion destabilization.
• These acid-responsive Pickering emulsions are suitable for water-sensitive applications.
• Potential applications include oil-based drilling fluids and other systems requiring tunable emulsion stability.