Formation of Liquid Marbles Using pH-Responsive Particles: Rolling vs Electrostatic Methods.

Area of Science:

• Colloid and Surface Science
• Materials Science
• Polymer Chemistry

Background:

• pH-responsive polymers enable tunable surface properties of colloidal particles.
• Liquid marbles (LMs) are droplets coated with particles, offering unique containment properties.
• Controlling particle surface chemistry is crucial for effective LM fabrication.

Purpose of the Study:

• To investigate the influence of pH on the properties of poly[2-(diethylamino)ethyl methacrylate] (PDEA)-stabilized polystyrene (PS) particles.
• To evaluate the efficacy of these particles as stabilizers for liquid marble formation using different methods.
• To correlate the surface characteristics of dried PDEA-PS powders with their performance in LM fabrication.

Main Methods:

• Aqueous dispersions of PS particles with PDEA stabilizers were prepared at pH 3.0 and pH 10.0.
• Particles were dried, ground into powders, and characterized for morphology and surface properties.
• Liquid marbles were fabricated using both rolling and electrostatic methods with distilled water droplets.

Main Results:

• Powder from pH 3.0 dispersion was hydrophilic, forming colloidal crystal grains; water droplets were absorbed.
• Powder from pH 10.0 dispersion was hydrophobic, forming amorphous aggregates; stable liquid marbles were formed by rolling.
• In the electrostatic method, pH 3.0 powder formed aqueous dispersion droplets, while pH 10.0 aggregates did not adhere.

Conclusions:

• The pH-dependent surface properties of PDEA-PS particles dictate their suitability for liquid marble stabilization.
• Hydrophobic particles (pH 10.0) are effective for LM formation via rolling, while hydrophilic particles (pH 3.0) are not.
• The rolling method is more effective for LM fabrication with these hydrophobic PDEA-PS powders compared to the electrostatic method.