Controlling the Structure of Supraballs by pH-Responsive Particle Assembly

Area of Science:

• Materials Science
• Colloid Science
• Nanotechnology

Background:

• Supraballs are colloidal particles whose properties depend on the arrangement of constituent colloids.
• Controlling this colloidal assembly during formation is key to tuning supraball characteristics.
• Current methods lack precise control over colloidal ordering during supraball fabrication.

Purpose of the Study:

• To introduce a novel method for controlling colloidal assembly in supraballs.
• To demonstrate the tunability of supraball properties through pH-induced dispersity changes.
• To enable broader applications of supraballs by tailoring their structural and mechanical attributes.

Main Methods:

• Fabrication of supraballs via drying of aqueous colloidal dispersions on super-liquid-repellent surfaces.
• Utilizing pH-responsive polystyrene microparticles functionalized with poly[2-(diethylamino)ethyl methacrylate].
• Controlling colloid dispersity and assembly by adjusting the pH of the dispersion (pH 3 vs. pH 10).

Main Results:

• Spherical supraballs with densely packed colloids formed at pH 3.
• Oblate supraballs with disordered colloids formed at pH 10 due to particle aggregation.
• Demonstrated pH-dependent control over supraball shape, crystallinity, and porosity.

Conclusions:

• The pH-mediated control of colloid dispersity offers a versatile method for fabricating tunable supraballs.
• This approach allows for the rational design of supraballs with specific mechanical and structural properties.
• The eco-friendly, energy-efficient fabrication method on superamphiphobic surfaces opens new avenues for supraball applications.