Electrorheological operation of low-/high-permittivity core/shell SiO 2/au nanoparticle microspheres for display media

Chung Lin Li, Jem Kun Chen*, Shih Kang Fan, Fu-Hsiang Ko, Feng Chih Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


In this study, we synthesized core/shell structures comprising monodisperse 3-μm SiO 2 microspheres and gold nanoparticles (AuNPs, ca. 6.7 nm) as the core and shell components, respectively. Using a layer-by-layer cross-linking process with a dithiol cross-linking agent, we prepared low-permittivity AuNP-encapsulated high-permittivity SiO 2 core/shell microspheres with variable AuNP shell thicknesses. The dispersivity of the microspheres in solution was enhanced after grafting poly(ethylene glycol) monomethyl ether thiol (PEG-SH) onto the AuNP layer on the SiO 2 microspheres. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed sesame ball-like structures for these SiO 2@AuNP@PEG microspheres. We encapsulated aqueous dispersions of these SiO 2@AuNP microspheres into sandwich structured displays (SSDs) to investigate their electrorheological properties, observing reversibly electroresponsive transmittance that is ideally suited for display applications. Increasing the thickness of the AuNP layer dramatically enhanced the stringing behavior of the SiO 2 microspheres, resulting in increased transmittance of the SSD. The response time of the electroresponsive electrorheological fluids also decreased significantly after modifying the SiO 2 with the AuNP layers. The effective permittivities of these composites could be predicted from the real (έ) and imaginary (έ́) parts of the Clausius-Mossotti formalism.

Original languageEnglish
Pages (from-to)5650-5661
Number of pages12
JournalACS Applied Materials and Interfaces
Issue number10
StatePublished - 24 Oct 2012


  • SiO microsphere
  • core/shell
  • electrorheology
  • gold nanoparticle

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