posted on 2022-03-17, 17:05authored byBishnu
P. Khanal, Eugene R. Zubarev
This
manuscript describes a universal method for the spontaneous
self-assembly of nanostructures ranging from 2–4 nm spherical
particles to ∼440 nm long anisotropic nanorods into ring-like
superstructures. The nanostructures composed of Au, Pt, and Pd as
surface materials were synthesized in an aqueous cetyltrimethyl ammonium
bromide (CTAB) solution. The ligand exchange technique with 4-mercaptophenol
was applied to replace CTAB from the surface of nanostructures with
a functional thiol. The esterification reaction was carried out to
covalently attach carboxy-terminated long-chain polystyrene (PS) molecules
to the surface of nanostructures. The high grafting density of PS
chains around nanocrystals made them highly soluble in a wide range
of organic solvents. When a drop of nanostructure solution in a volatile
nonpolar solvent was dried on a solid surface, the nanostructures
spontaneously arranged themselves in the form of ring-like assemblies.
The condensation of microscopic water droplets from the atmosphere
on the surface of an evaporating solvent creates templates for the
self-assembly of nanostructures into rings. We demonstrate that this
self-assembly method is highly universal and can be extended to various
nanostructures regardless of their shapes, sizes, and surface materials.