Facile Methods to Coat Polystyrene and Silica Colloids with Metal

Abstract

To avoid the complex core surface functionalization or pretreatment that is necessary in order to coat latex and silica colloids with a uniform, complete metal shell, the solvent‐assisted route has been explored to prepare a complete metal (Ag or Au) shell with controlled thickness on polystyrene (PS) colloids and the electroless plating approach, based on electrostatic attraction, has been explored to prepare a complete silver shell with controlled thickness on silica colloids. Without any additional surface treatment, the as‐prepared complex core–shell colloids can be crystallized directly into long‐range‐ordered structures with photonic bandgaps, as reported here for the first time. These ordered structures may find potential applications as substrates or physical systems for the enhancement of Raman scattering studies, besides applications as photonic crystals. The optical plasmon resonance of the composite core–shell colloids changes with metal shell thickness, the wavelength varying over hundreds of nanometers. Our coating routes are facile and versatile, and can be extended to coat PS and silica colloids with any other metal whose ion or complex can be reduced in solution.

Enhancing the radiation efficiency of dye doped whispering gallery mode microresonators

“…This enhancement is more pronounced for wavelengths between 610 nm and 620 nm, even though the maximum emission of the organic dye used to dope the sphere is around 590 nm. This can be explained by the significant decrease of the absorption of polystyrene from 590 to 620 nm as shown by Zhang et al [26]. The analysis of the most intense resonance mode in both cases by fitting with a Gaussian function revealed an increase of the effective Q-factor (Q = λ/δλ) from 1170 for the free floating sphere, comparable to previously reported Q-factor in the literature for similar sphere size and material in water [25], to 1560 for the same sphere once attached to the MOF tip, resulting in a 33% increase.…”

Preparation of Silica-Gold Composite particles

“…Recently, novel preparation routes for composite materials have been proposed to simplify the conventional complex reaction process or to obtain dense and uniform metal layers: sono-chemical deposition [6], electroless plating [7], electrostatic attraction [8] The water used in this study was deionized by Milli-Q Plus system(Millipore, France), having18.2MΩ electrical resistivity.…”

Preparation and Optical Properties of PS @Au-Cu Core-Shell Nano Composite

“…It is also very interesting to reduce the interlay spacing to atomic level and replace the inner and outer shell of the concentric nanoshell with different kinds of metal, namely, alloy, and control the resulting surface plasmon by varying the alloying component. The tuning of SPR in intensity and wavelength is desired for the applications of SPR [5][6][7] The layered nanoparticle with a dielectric core and a metallic nanoshell, known as a metal nanoshell, provides a tunable geometry in which the surface plasmon wavelength at the nanoshell surface can be precisely controlled by varying the core/shell ratio. For example, the surface plasmon resonance of a silica core-gold shell nanoshell can be varied over hundreds of nanometers in wavelength,across the visible and into the infrared region of the spectrum [6,7].…”

“…The tuning of SPR in intensity and wavelength is desired for the applications of SPR [5][6][7] The layered nanoparticle with a dielectric core and a metallic nanoshell, known as a metal nanoshell, provides a tunable geometry in which the surface plasmon wavelength at the nanoshell surface can be precisely controlled by varying the core/shell ratio. For example, the surface plasmon resonance of a silica core-gold shell nanoshell can be varied over hundreds of nanometers in wavelength,across the visible and into the infrared region of the spectrum [6,7]. Recently, the studies of the plasmon energies of the concentric metal nanoshell structure supply us a new technique to manipulate the surface plasmon resonance [8].…”