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Directional Templating Mechanisms of Anisotropic Nanoparticles Using Poly(pyromellitic dianhydride‑p‑phenylenediamine)
journal contribution
posted on 2016-05-24, 00:00 authored by Victor
M. Kariuki, Julien A. Panetier, Jürgen Schulte, Omowunmi A. SadikThis
study reports for the first time the use of poly(pyromellitic
dianhydride-p-phenylenediamine) (PPDD) as a reducing
and stabilizing agent, immobilization matrix, and directional template
for the synthesis of anisotropic silver nanoparticles (AgNPs). The
work also provides a new physical insight into the mechanisms of directional
templating of anisotropic nanoparticles based on diffusion-limited
aggregate model and coalescence growth mechanism. Molecular dynamics
simulations and density functional theory calculations were performed
to provide insight into possible conformations of the PPDD monomer.
Anisotropic (nonspherical) peanut-shaped nanorods and dendritic nanostructures
were prepared in situ using varying concentrations of precursors from
0.1 to 1.0% w/v within PPDD matrix. The PPDD served as the reducing
and directional template, thus enforcing preferential orientation.
The mechanism of formation and growth of the polymer-mediated anisotropic
nanoparticles was confirmed using transmission electron microscopy,
UV–vis near-infrared absorption spectra (UV–vis-NIR),
and X-ray diffraction. The size distribution of the nanoparticles
was found to be 6–10 (0.1% w/v), 20 (0.2% w/v), and 70–100
nm (0.5% w/v). The UV–vis-NIR spectra confirmed the existence
of transverse and longitudinal surface plasmon resonance according
to Mie theory. The anisotropic growth of dendritic/nanorods AgNPs
could be attributed to diffusion-limited aggregate model and coalescence
growth mechanism. 111 planes were the most predominant structures,
indicating inhibition of growth along the perpendicular axis by PPDD,
thus conferring the preferred coalescence orientation of nanoparticle
parallel on the film.
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Keywords
coalescence orientationAnisotropic NanoparticlesinsightdianhydrideMolecular dynamics simulationsDirectional Templating Mechanismsstudy reportspeanut-shaped nanorodstheory calculationssize distributiontemplatePPDD matrixphenylenediamine111 planesanisotropic silver nanoparticlesanisotropic nanoparticlestransmission electron microscopydiffusion-limitedMie theoryAgNPsurface plasmon resonanceUVcoalescence growth mechanismdendritic nanostructuresanisotropic growthPPDD monomerimmobilization matrixX-ray diffractionspectrapolymer-mediated anisotropic nanoparticlesmodel
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