posted on 2024-03-12, 14:46authored byThomas
M. R. Wayman, Vladimir Lomonosov, Emilie Ringe
Mg nanoparticles
are an emerging plasmonic material due to Mg’s
abundance and ability to sustain size- and shape-dependent localized
surface plasmon resonances across a broad range of wavelengths from
the ultraviolet to the near infrared. However, Mg nanoparticles are
colloidally unstable due to their tendency to aggregate and sediment.
Nanoparticle aggregation can be inhibited by the addition of capping
agents that impart surface charges or steric repulsion. Here, we report
that the common capping agents poly(vinyl) pyrrolidone (PVP), polyethylene
glycol (PEG), cetyltrimethylammonium bromide (CTAB), and sodium dodecyl
sulfate (SDS) interact differently and have varied effects on the
aggregation and colloidal stability of Mg nanoparticles. Nanoparticles
synthesized in the presence of PVP showed improvements in colloidal
stability and reduced aggregation, as observed by electron microscopy
and optical spectroscopy. The binding of PVP was confirmed through
infrared and X-ray photoelectron spectroscopy. The influence of PVP
on the reduction of di-n-butyl magnesium was evaluated
through analysis of particle size distribution and Mg yield as a function
of reaction time, reducing agent, and temperature. Furthermore, the
presence of PVP drastically changes the growth pattern of metallic
Mg structures obtained from the reduction of the Grignard reagents
butylmagnesium chloride and phenylmagnesium chloride by lithium naphthalenide:
large polycrystalline aggregates and well-separated faceted nanoparticles
grow without and with PVP, respectively. This study provides new synthetic
routes that generate colloidally stable and well-dispersed Mg nanoparticles
for plasmonic and other applications.