Modulation of Buckling Dynamics in Nanoparticle Laden Droplets Using External Heating

Area of Science:

• Fluid dynamics
• Materials science
• Nanotechnology

Background:

• Contact-free droplet drying is vital in spray drying and pharmaceutics.
• Controlling final sample morphology during drying presents significant challenges.
• Acoustically levitated nanosilica droplets form porous shells due to solvent evaporation and particle agglomeration.

Purpose of the Study:

• Investigate the buckling dynamics of acoustically levitated nanodroplets.
• Understand the role of capillary pressure in shell buckling and final structure formation.
• Explore methods to control or reinitialize buckling for morphology manipulation.

Main Methods:

• Acoustic levitation of nanosilica droplets.
• Controlled evaporation and particle agglomeration studies.
• Analysis of shell buckling mechanisms and cavity formation dynamics.

Main Results:

• Capillary pressure drives shell buckling, forming ring and bowl structures.
• Acoustics flattens droplets, initiating buckling.
• Mixed nanocolloids (SDS + nanosilica) reduce evaporation and enhance shell strength, hindering buckling.
• Laser heating or anilinium hydrochloride addition can reinitialize buckling by altering evaporation and aggregate morphology.

Conclusions:

• Droplet drying morphology is governed by buckling dynamics, influenced by particle properties and evaporation rates.
• Cavity formation during buckling leads to diverse final structures.
• Evaporation through nanoscale pores controls cavity growth universally, regardless of heating or nanoparticle type.