Formation of highly ordered nanostructures by drying micrometer colloidal droplets

Area of Science:

• Materials Science
• Nanotechnology
• Colloid Science

Background:

• Nanoparticles serve as versatile building blocks for functional structures.
• Spray-drying is a technique for forming aggregates from colloidal particles.

Purpose of the Study:

• To investigate the formation of crystal-like structures using spray-drying of nanoparticle building blocks.
• To explore the production of quasicrystalline, porous, and hollow aggregates.
• To analyze the influence of particle size and zeta potential on aggregate formation.

Main Methods:

• Utilizing a spray-drying technique with uniform spherical polystyrene (PS) particles.
• Employing PS particles with varied zeta potentials as templates for inorganic colloidal particles.
• Investigating the effect of monodisperse versus mixed-size colloidal particles in precursor suspensions.

Main Results:

• Spray-drying uniform particles yielded tightly packed aggregates with simple or broken symmetries (quasicrystalline).
• Highly ordered porous and hollow aggregates were formed using PS particles as templates.
• Quasicrystalline structures were exclusively formed using monodisperse colloidal particles; mixed sizes led to different packing.

Conclusions:

• Spray-drying is an effective method for creating ordered nanoparticle aggregates, including quasicrystalline structures.
• Monodispersity of colloidal particles is crucial for achieving quasicrystalline forms.
• A geometric model accurately predicts the formation of these quasicrystalline structures based on sphere packing principles.