Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading

Abstract

Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres. This versatile two-step method provides more fine control than methods previously demonstrated in the literature. These decorated PS spheres are of interest for a number of applications, such as catalytic reactions where the PS spheres provide a support for the dispersion, stabilization, and recovery of NP catalysts. The catalytic properties of these PS@NPs spheres were assessed by studying the catalytic degradation of azo dyes, an environmental contaminant detrimental to eye health. The PS@NPs spheres were used in multiple, sequential catalytic reactions while largely retaining the NP coating.

How to Enhance Gas Removal from Porous Electrodes?

“…For this purpose, we parametrize the general model for the specific case of alkaline oxygen evolution on a structured Nickel electrode in KOH. For the electrode structure, which is represented by L and a , we assume an inverse opal structure333435. This structure can be made by templating with polystyrene spheres, electrodeposition of Nickel in the void between the spheres and subsequent removal of the templates.…”

“…This structure can be made by templating with polystyrene spheres, electrodeposition of Nickel in the void between the spheres and subsequent removal of the templates. The advantages of this structure are that it is well defined, allows direct control over the structural parameters (radius of the inverse opals, thickness of the layer via number of layers) and can easily be manufactured333435. The parameters used in the following are summarized in Table 1.…”

Verifying the Structure and Composition of Prepared Porous Catalytic Supports

“…The method for preparing NPs loaded into a 3-D porous support involved the preparation of NP coated spherical polystyrene templates, self-assembly of these templates, infiltration with a support matrix, and removal of the sacrificial templates. The NPs (Pd or Pt) were mixed with the polystyrene templates at room temperature for 20 min to facilitate the first step of this process [10,12] . These decorated polymer spheres were purified to remove excess NPs, and self-assembled into thin films using either air-water interface self-assembly [10,13] , drop casting [12] , spin coating [14] , or vacuum filtration [15] .…”

“…The NPs (Pd or Pt) were mixed with the polystyrene templates at room temperature for 20 min to facilitate the first step of this process [10,12] . These decorated polymer spheres were purified to remove excess NPs, and self-assembled into thin films using either air-water interface self-assembly [10,13] , drop casting [12] , spin coating [14] , or vacuum filtration [15] . A support matrix was filled into the interstitial spaces between these sacrificial templates, and the polymer was then removed to produce nanostructured supports coated with NPs.…”

“…This support matrix was deposited by either material specific electrochemical deposition [13] or sol-gel techniques [15] . Templates were removed either by high temperature air oxidation (>300°C for >8 h) or room temperature digestion in organic or alkaline solutions [10][11][12][13][14][15] .…”