5 research outputs found
Environmentally Friendly High-Near-Infrared Reflectance Blue Pigment YIn<sub>0.9â<i>x</i></sub>Mn<sub>0.1</sub>M<sub><i>x</i></sub>O<sub>3âδ</sub> Based on Li/Zn Doping
In
this work, the Li/Zn-doped near-infrared reflective
inorganic
blue pigment YIn0.9âxMn0.1MxO3âδ (M = Li/Zn, x = 0â0.4) was synthesized by the high-temperature
solid-state reaction method. The phase structures, morphologies, color
properties and optical properties of synthetic pigments were characterized
by X-ray diffractometer (XRD), scanning electron microscope (SEM),
CIE1976 color space system, UVâvis-NIR spectrophotometer, and
other instruments. All the doped samples have a hexagonal structure
with space group P63cm (185). Compared
with YIn0.9Mn0.1O3 (b* = â45.91), Li/Zn doped pigments have richer blue hues (b* is ranged from â29.59 to â55.14), which
can meet the needs of publicâs demands for blue hues. The NIR
solar reflectance (R*) of all the samples are above
70%, and the highest R* with different doping concentrations
can reach 86% (M = Li, x = 0.2), which is about 16%
higher than YIn0.9Mn0.1O3. YIn0.9âxMn0.1MxO3âδ (M = Zn/Li, x = 0â0.4) are indicated to possess higher near-infrared
solar reflectivity than other blue compounds, including commercial
products. The surface temperature difference between the Li-doped
(x = 0.2)/Zn-doped (x = 0.1) paints
and commercial ultramarine paint can reach about 20 and 10 °C,
respectively. The above properties ensure the potential applications
of environmentally friendly YIn0.9âxMn0.1MxO3âδ pigments with a rich blue-hue in the field of energy-saving materials
Tuning Molecular-Level Polymer Conformations Enables Dynamic Control over Both the Interfacial Behaviors of Ag Nanocubes and Their Assembled Metacrystals
In surface chemistry-directed
nanoparticle self-assembly, it remains
challenging to continuously modulate nanoparticle behavior at the
oil/water interface without replacing surface functionality or particle
morphology. Here, we utilize solvent-tunable molecular-level polymer
conformation changes to achieve âmultiple metacrystals using
one nanoparticle with one chemical functionalityâ. We use Ag
nanocubes functionalized with a mixed monolayer of thiol-terminated
polyÂ(ethylene glycol) (PEG) and hexadeÂcaneÂthiol
(C16). We continuously modulate PEG conformation from swollen to coiled
states by decreasing solvent polarity, whereas C16 promotes nanocube
dispersion in organic carrier solvents. Such PEG conformation changes
drive Ag nanocubes to adopt tilted, standing, and planar configurations
at the oil/water interface, with their interfacial positions changing
from halfway across the interface to almost immersed within the oil
phase. We also identify four specific polarities which enable Ag nanocubes
to assemble into large-area metacrystals with linear, hexagonal, and
square close-packed lattices. Our work establishes an innovative strategy
to achieve robust tunability of nanoparticle interfacial behavior
and unprecedented modulation of metacrystal structure
Flexible Three-Dimensional Anticounterfeiting Plasmonic Security Labels: Utilizing <i>Z</i>âAxis-Dependent SERS Readouts to Encode Multilayered Molecular Information
Current
surface-enhanced Raman scattering (SERS)-based anticounterfeiting
strategies primarily encode molecular information in single two-dimensional
(2D) planes and under-utilize the three-dimensionality (3D) of plasmonic
hot spots. Here, we demonstrate a 3D SERS anticounterfeiting platform,
extending âlayered securityâ capabilities from 2D to
3D. We achieve this capability by combining 3D candlestick microstructures
with 3D hyperspectral SERS imaging to fully resolve at least three
layers of encoded information within the same 2D area along the <i>z</i>-axis, notably using only a single probe molecule. Specific
predesigned covert images can only be fully recovered via SERS imaging
at predetermined <i>z</i> values. Furthermore, our 3D SERS
anticounterfeiting security labels can be fabricated on both rigid
and flexible substrates, widening their potential usages to curved
product surfaces and banknotes
A Chemical Approach To Break the Planar Configuration of Ag Nanocubes into Tunable Two-Dimensional Metasurfaces
Current
plasmonic metasurfaces of nanocubes are limited to planar
configurations, restricting the ability to create tailored local electromagnetic
fields. Here, we report a new chemical strategy to achieve tunable
metasurfaces with nonplanar nanocube orientations, creating novel
lattice-dependent field localization patterns. We manipulate the interfacial
behaviors of Ag nanocubes by controlling the ratio of hydrophilic/hydrophobic
molecules added in a binary thiol mixture during the surface functionalization
step. The nanocube orientation at an oil/water interface can consequently
be continuously tuned from planar to tilted and standing configurations,
leading to the organization of Ag nanocubes into three unique large-area
metacrystals, including square close-packed, linear, and hexagonal
lattices. In particular, the linear and hexagonal metacrystals are
unusual open lattices comprising nonplanar nanocubes, creating unique
local electromagnetic field distribution patterns. Large-area âhot
hexagonsâ with significant delocalization of hot spots form
in the hexagonal metacrystal. With a lowest packing density of 24%,
the hexagonal metacrystal generates nearly 350-fold stronger surface-enhanced
Raman scattering as compared to the other denser-packing metacrystals,
demonstrating the importance of achieving control over the geometrical
and spatial orientation of the nanocubes in the metacrystals
Direct Metal Writing and Precise Positioning of Gold Nanoparticles within Microfluidic Channels for SERS Sensing of Gaseous Analytes
We
demonstrate a one-step precise direct metal writing of well-defined
and densely packed gold nanoparticle (AuNP) patterns with tunable
physical and optical properties. We achieve this by using two-photon
lithography on a Au precursor comprising polyÂ(vinylpyrrolidone) (PVP)
and ethylene glycol (EG), where EG promotes higher reduction rates
of AuÂ(III) salt via polyol reduction. Hence, clusters of monodisperse
AuNP are generated along raster scanning of the laser, forming high-particle-density,
well-defined structures. By varying the PVP concentration, we tune
the AuNP size from 27.3 to 65.0 nm and the density from 172 to 965
particles/Îźm<sup>2</sup>, corresponding to a surface roughness
of 12.9 to 67.1 nm, which is important for surface-based applications
such as surface-enhanced Raman scattering (SERS). We find that the
microstructures exhibit an SERS enhancement factor of >10<sup>5</sup> and demonstrate remote writing of well-defined Au microstructures
within a microfluidic channel for the SERS detection of gaseous molecules.
We showcase in situ SERS monitoring of gaseous 4-methylbenzenethiol
and real-time detection of multiple small gaseous species with no
specific affinity to Au. This one-step, laser-induced fabrication
of AuNP microstructures ignites a plethora of possibilities to position
desired patterns directly onto or within most surfaces for the future
creation of multifunctional lab-on-a-chip devices