Asymmetric Colloidal Janus Particle Formation Is Core-Size-Dependent.

Area of Science:

• Materials Science
• Colloid Science
• Nanotechnology

Background:

• Janus particles possess unique bifunctional properties due to asymmetric surface chemistry.
• Particle size is crucial for applications in drug delivery and catalysis.
• The influence of carboxylate coating on Janus particle size is known, but core size effects are less defined.

Purpose of the Study:

• To investigate the impact of carboxylated polystyrene (cPS) core size on cPS-silica Janus particle morphology.
• To understand how varying cPS core sizes and silica shell sizes influence particle shape and dimensions.

Main Methods:

• Synthesis of cPS-silica Janus particles using varying cPS core sizes and two silica shell sizes.
• Characterization using electron microscopy (EM) for morphology and dynamic light scattering (DLS) for size analysis.

Main Results:

• Particle morphology depends on the relative sizes of the cPS core and the silica shell.
• Partially encapsulated Janus particles form when the cPS core is significantly smaller than the silica shell.
• Raspberry-like structures form when the cPS core is larger than or equal to the silica shell.
• Scalable cPS-silica Janus particles ranging from approximately 100-500 nm were achieved.

Conclusions:

• cPS core size is a critical determinant of cPS-silica Janus particle formation and morphology.
• Controlled synthesis allows for tunable Janus particle sizes for specific applications.
• These nanoscale Janus particles offer potential for multifunctional delivery systems and catalysis.