Three-dimensional periodic structures of gold nanoclusters in the interstices of sub-100 nm polymer particles toward surface-enhanced Raman scattering

Yahata, Ayumi; Ishii, Haruyuki; Nakamura, Kôsuke; Watanabe, Kanako; Nagao, Daisuke

doi:10.1016/j.apt.2019.09.003

Cited by 7 publications

(2 citation statements)

References 33 publications

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“…As such, colloidal crystals with interparticle spacings on the length scales of visible wavelengths of light are also referred to as photonic crystals, and they have been studied for various applications in optics such as color pigments, − anticounterfeiting labels, , and colorimetric sensors. , Bottom-up fabrication methods for three-dimensional (3D), multilayered, colloidal crystals have been studied extensively. Self-assembled crystals can be fabricated on a large (∼cm 2 ) scale, , and the number of layers is easily controlled. − However, in general, the rearrangement of building blocks in close-packed crystals is barely possible because the building blocks do not have any free space to move. This results in static optical properties, meaning that the Bragg reflection wavelengths and intensities cannot easily be tuned.…”

Section: Introductionmentioning

confidence: 99%

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Namigata,

Welling,

Watanabe

et al. 2023

ACS Appl. Opt. Mater.

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Yolk−shell particles consist of a hollow shell enclosing a mobile inner particle. Colloidal crystals made from yolk−shell particles are a unique structure, in which the disorder of highly scattering inner particles can be controlled, which allows for optical switching. In this work, yolk−shell particles were synthesized and assembled into an ordered structure. External alternating current (AC) electric fields were used to control the inner particle motion, as observed by confocal microscopy and optical reflection measurements. The colloidal crystal of yolk−shell particles showed long-range order due to the assembled shells but decreased short-range order due to the Brownian motion of inner particles. Using an AC electric field (25 V/mm), all inner particles moved electrophoretically, resulting in ordered inner-particle arrangements. This enabled the fast, reversible switching of the Bragg reflection intensities. Next, we investigated how a decreased short-range order when the field is off influenced the switchability. The largest optical intensity change was achieved with a high ionic strength (10 mM) and a small coreto-shell size ratio (∼0.3). Our proof-of-concept results show promise that with further optimization, even more strongly switchable photonic crystals can be achieved in this way.

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Section: Introductionmentioning

confidence: 99%

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Namigata,

Welling,

Watanabe

et al. 2023

ACS Appl. Opt. Mater.

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“…Monodispersity in particle size distribution is important for extending the practical application scope of particulate functional materials. − The core–shell structure is a type of particle structure in which both monodispersity and functionality of particles are achieved. − In the field of column packing materials for high-performance liquid chromatography (HPLC), , monodisperse core particles coated with a mesoporous shell have been extensively used to enhance the separation performance in HPLC.…”

Section: Introductionmentioning

confidence: 99%

Correlation of Secondary Particle Number with the Debye–Hückel Parameter for Thickening Mesoporous Silica Shells Formed on Spherical Cores

et al. 2021

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Mesoporous silica shells were formed on nonporous spherical silica cores during the sol−gel reaction to elucidate the mechanism for the generation of secondary particles that disturb the efficient growth of mesoporous shells on the cores. Sodium bromide (NaBr) was used as a typical electrolyte for the sol−gel reaction to increase the ionic strength of the reactant solution, which effectively suppressed the generation of secondary particles during the reaction wherein a uniform mesoporous shell was formed on the spherical core. The number of secondary particles (N 2nd ) generated at an ethanol/water weight ratio of 0.53 was plotted against the Debye−Huckel parameter κ to quantitatively understand the Debye screening effect on secondary particle generation. Parameter κa, where a is the average radius of the secondary particles finally obtained in the silica coating, expresses the trend in N 2nd at different concentrations of ammonia and NaBr. N 2nd was much lower than that expected theoretically from the variation of secondary particle sizes at a constant Debye− Huckel parameter. A similar correlation with κa was observed at the high and low ethanol/water weight ratios of 0.63 and 0.53, respectively, with different hydrolysis rate constants. The good correlation between N 2nd and κa revealed that controlling the ionic strength of the silica coating is an effective approach to suppress the generation of secondary particles for designing mesoporous shells with thicknesses appropriate for their application as high-performance liquid chromatography column packing materials.

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An experimental study on emulsion polymerization for formation of monodisperse particles smaller than 50 nm

et al. 2022

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Three-dimensional periodic structures of gold nanoclusters in the interstices of sub-100 nm polymer particles toward surface-enhanced Raman scattering

Cited by 7 publications

References 33 publications

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Correlation of Secondary Particle Number with the Debye–Hückel Parameter for Thickening Mesoporous Silica Shells Formed on Spherical Cores

An experimental study on emulsion polymerization for formation of monodisperse particles smaller than 50 nm

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Three-dimensional periodic structures of gold nanoclusters in the interstices of sub-100 nm polymer particles toward surface-enhanced Raman scattering

Cited by 7 publications

References 33 publications

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Switchable Bragg Reflections via Controllable Inner Particle Motion in Yolk–Shell Colloidal Crystals

Correlation of Secondary Particle Number with the Debye–Hückel Parameter for Thickening Mesoporous Silica Shells Formed on Spherical Cores

An experimental study on emulsion polymerization for formation of monodisperse particles smaller than 50 nm

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Three-dimensional periodic structures of gold nanoclusters in the interstices of sub-100 nm polymer particles toward surface-enhanced Raman scattering