Multifunctional colloids with optical, magnetic, and superhydrophobic properties derived from nucleophilic substitution-induced layer-by-layer assembly in organic media

Miseon Yoon, Younghoon Kim, Jinhan Cho

Research output: Contribution to journalArticle

65 Citations (Scopus)

Abstract

We demonstrate the successful preparation of multifunctional silica colloids by coating with 2-bromo-2-methylpropionic acid (BMPA)-stabilized quantum dots (BMPA-QDs) and BMPA-stabilized iron oxide particles (BMPA-Fe 3O4), along with amine-functionalized poly(amidoamine) (PAMA) dendrimers, using layer-by-layer (LbL) assembly based on a nucleophilic substitution (NS) reaction between the bromo and amine groups in organic media. The QDs and Fe3O4 nanoparticles used in this study were directly synthesized in a nonpolar solvent (chloroform or toluene), and the oleic acid stabilizers were exchanged with BMPA in the same solvent to minimize chemical and physical damage to the nanoparticles. The direct adsorption of nanoparticles via an NS reaction in organic solvent significantly increased the packing density of the nanoparticles in the lateral dimensions because electrostatic repulsion between neighboring nanoparticles was absent. The multifunctional colloids densely coated with nanoparticles showed excellent characteristics (i.e., superparamagnetism, photoluminescence, and magneto-optical tuning properties) with long-term stability in nonpolar solvents. Furthermore, deposition of the nanocomposite colloids onto flat substrates, followed by coating with a low-surface-energy fluoroalkylsilane polymer, produced a densely packed rugged surface morphology in the colloidal films that displayed superhydrophobic properties with water contact angles greater than 150°.

Original languageEnglish
Pages (from-to)5417-5426
Number of pages10
JournalACS nano
Volume5
Issue number7
DOIs
Publication statusPublished - 2011 Jul 26

Keywords

  • colloidal substrate
  • layer-by-layer assembly
  • magnetic nanoparticles
  • nucleophilic substitution reaction
  • quantum dot nanoparticles

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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