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Free‐Standing Photonic Glasses Fabricated in a Centrifugal Field
Author(s) -
Chen Mengdi,
Fischli Danja,
Schertel Lukas,
Aubry Geoffroy J.,
Häusele Benedikt,
Polarz Sebastian,
Maret Georg,
Cölfen Helmut
Publication year - 2017
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201701392
Subject(s) - colloid , materials science , photonics , electrolyte , polystyrene , nanoparticle , light scattering , chemical engineering , dynamic light scattering , nanotechnology , chemical physics , scattering , polymer , optics , chemistry , optoelectronics , composite material , electrode , physics , engineering
One efficient method to obtain disordered colloidal packing is to reduce the stability of colloidal particles by adding electrolytes to the colloidal dispersions. But the correct amount of additional electrolytes must be found empirically. Here, the effect of CaCl 2 on polystyrene colloidal dispersions is studied, and a link between the amount of CaCl 2 and the corresponding glassy colloidal structure is quantitatively built. A threshold concentration of CaCl 2 is found by dynamic light scattering. When exceeding this threshold, different nanoparticle oligomers are observed in the dispersions by analytical ultracentrifugation. The second objective is to achieve free‐standing samples, which is required for many optical measurements. A universal method is established, using a centrifugal field to produce robust samples by polymerizing coassembled hydrophilic monomers to form a network, which traps the glassy colloidal structures. Photon time of flight measurements shows that the CaCl 2 concentration threshold should not be exceeded. Otherwise an optical shortcut may take place. Thus, the work provides a feasible universal route to prepare macroscopic free‐standing photonic glasses from electrostatically stabilized nanoparticles, suitable for further optical investigation.