Contact angle as a powerful tool in anisotropic colloid synthesis

Area of Science:

• Colloid and interface science
• Materials chemistry
• Surface science

Background:

• Nucleation and growth is a key method for colloid preparation.
• Substrate contact angle significantly influences particle morphology.
• Controlling particle shape and properties is crucial for advanced material applications.

Purpose of the Study:

• To investigate the nucleation and growth of 3-methacryloxypropyltrimethoxysilane (MPTMS) on different substrates.
• To explore the influence of substrate properties on colloid morphology and characteristics.
• To develop index-matched engulfed-sphere colloids for advanced microscopy and self-assembly studies.

Main Methods:

• Synthesis of MPTMS colloids via nucleation and growth on Stöber and MPTMS* spheres.
• Contact angle measurements to analyze wetting behavior.
• Index-matching of colloids using polar and low-polar media, including cyclohexyl iodide (CHI).
• Confocal microscopy to track particle self-assembly and rotational diffusion.

Main Results:

• 'Snowman' particles with controllable morphology were formed on Stöber spheres.
• Line tension influences wetting in addition to surface tension.
• Highly reproducible and tunable 'engulfed-sphere' colloids were synthesized on MPTMS* spheres.
• Engulfed-sphere colloids were successfully index-matched and self-assembled into plastic phases.

Conclusions:

• The choice of substrate in nucleation and growth significantly dictates colloid morphology.
• Engulfed-sphere colloids offer tunable properties and are suitable for advanced imaging.
• This work presents a new method for creating index-matched colloids and studying their self-assembly dynamics.