Tri-Phasic Size- and Janus Balance-Tunable Colloidal Nanoparticles (JNPs).

Area of Science:

• Materials Science
• Polymer Chemistry
• Colloid and Surface Chemistry

Background:

• Janus nanoparticles (JNPs) offer unique interfacial properties for applications like Pickering emulsions.
• Controlling nanoparticle morphology and responsiveness is crucial for advanced material design.

Purpose of the Study:

• To synthesize triphasic, size- and Janus balance (JB)-tunable nanoparticles (JNPs).
• To investigate the temperature- and pH-responsive behavior of these JNPs.
• To explore the application of JNPs in forming and destabilizing Pickering emulsions.

Main Methods:

• Two-step emulsion polymerization of pentafluorostyrene (PFS), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and n-butyl acrylate (nBA) using nanoparticle seeds.
• Utilizing the second-order lower critical solution temperature (II-LCST) transition of p(DMAEMA/nBA) for size and shape changes.
• Tuning Janus balance (JB) by controlling phase-separated copolymer morphologies.

Main Results:

• Successfully synthesized triphasic JNPs with tunable JB from 3.78 to 0.72.
• Demonstrated reversible size and shape changes of JNPs triggered by temperature (30-45 °C) and pH.
• JNPs effectively stabilized oil droplets in water at high pH, forming Pickering emulsions, and released oil at lower pH.

Conclusions:

• The synthesized JNPs exhibit controllable responsiveness to temperature and pH, enabling tunable interfacial properties.
• These JNPs are effective stabilizers for Pickering emulsions with reversible oil release capabilities.
• The developed method provides a pathway for creating advanced functional nanoparticles for emulsion applications.