Self-Assembly Mechanism of Complex Corrugated Particles

Area of Science:

• Materials Science
• Nanotechnology
• Physical Chemistry

Background:

• Inorganic nanoscale materials form microscale particles with complex geometries, but the underlying formation mechanism is not understood.
• Existing knowledge lacks a clear explanation for the self-assembly of nanoparticles into highly corrugated structures.

Purpose of the Study:

• To elucidate the self-assembly mechanism of inorganic nanoparticles into microscale particles with highly corrugated geometries.
• To investigate the factors influencing the morphology and complexity of self-assembled particles.

Main Methods:

• Experimental self-assembly of cadmium sulfide (CdS)-based nanoparticles (NPs) into hedgehog particles (HPs).
• Systematic variation of temperature, solvent, and reaction time to control particle morphology.
• Theoretical modeling and simulations incorporating electrostatic repulsion, van der Waals attraction, and kinetic parameters.

Main Results:

• Uniformly sized CdS-based HPs (1770 ± 180 nm) self-assembled from polydisperse NPs (1.0-4.0 nm).
• Particle morphology, including nanorods, aggregates, and HPs, was controlled by varying experimental conditions, yielding complexity indexes from 0 to 23.7.
• Theoretical models accurately predicted particle morphology and growth stages, including flower-like particles, and demonstrated generality with mixed CdS and cobalt oxide (Co3O4) NPs.

Conclusions:

• The formation of corrugated particles, including HPs, is driven by the thermodynamic preference of polydisperse NPs to attach to growing clusters, balancing electrostatic repulsion and van der Waals attraction.
• The proposed mechanism provides mechanistic insights essential for adapting HP structures for applications in energy storage, catalysis, and water treatment.
• Hedgehog particles exhibit remarkable dispersion stability in challenging solvents like liquid CO2.