Fabrication and Modeling of a Thermoreversible Modular Core-Shell Colloidal System

Area of Science:

• Materials Science
• Colloid Science
• Physical Chemistry

Background:

• Octadecyl-coated silica particles are used in rheological studies of colloidal gels.
• Existing synthesis methods lack reproducibility due to variable grafting densities and transition temperatures.

Purpose of the Study:

• To develop a more reproducible method for synthesizing octadecyl-coated silica particles.
• To achieve precise control over grafting density and interparticle interactions for model colloidal gel systems.

Main Methods:

• Utilized an amine-yne click-like reaction for grafting octadecyl chains onto silica particles.
• Suspended particles in tetradecane, exhibiting a reversible liquid-solid transition below 20 °C.
• Controlled grafting density by fine-tuning reaction conditions.

Main Results:

• Achieved high-fidelity grafting of octadecyl chains with precise control over density.
• Demonstrated a reversible liquid-solid transition below 20 °C, ideal for rheological studies.
• Interparticle interactions modeled as a superposition of temperature-dependent forces, validated by AFM.

Conclusions:

• The novel synthesis method provides a highly reproducible model system for colloidal gel studies.
• Precise tuning of interparticle potentials enables quantitative comparisons between experiments and simulations.
• This system minimizes rheological characterization complications like loading history and thixotropy.