Critical roles of cationic surfactants in the preparation of colloidal mesostructured silica nanoparticles: Control of mesostructure, particle size, and dispersion

Hironori Yamada, Chihiro Urata, Sayuri Higashitamori, Yuko Aoyama, Yusuke Yamauchi, Kazuyuki Kuroda

    Research output: Contribution to journalArticle

    37 Citations (Scopus)

    Abstract

    Mesoporous silica nanoparticles are promising materials for various applications, such as drug delivery and catalysis, but the functional roles of surfactants in the formation and preparation of mesostructured silica nanoparticles (MSN-as) remain to be seen. It was confirmed that the molar ratio of cationic surfactants to Si of alkoxysilanes (Surf/Si) can affect the degree of mesostructure formation (i.e., whether the mesochannels formed inside the nanoparticles actually pass through the outer surface of the particles), the particle diameter, and the dispersibility of MSN-as. Wormhole-like mesostructures formed with low Surf/Si ratios; however, the mesopores did not pass through the outer surface of the particles completely. At high Surf/Si ratios, the mesostructures extended. The particle diameter was 100 nm or larger at low Surf/Si ratios, and the primary particle diameter decreased as the Surf/Si ratio increased. This was because the surfactants enhanced the dispersity of the alkoxysilanes in water and the hydrolysis rate of the alkoxysilanes became faster, leading to an increased nucleation as compared to the particle growth. Moreover, primary particles aggregated at low Surf/Si ratios because of the hydrophobic interactions among the surfactants that were not involved in the mesostructure formation but were adsorbed onto the nanoparticles. At high Surf/Si ratios, the surfactant micelles were adsorbed on the surface of primary particles (admicelles), resulting in the dispersion of the particles due to electrostatic repulsion. In particular, molar ratios of 0.13 or higher were quite effective for the preparation of highly dispersed MSN-as. Surfactants played important roles in the mesostructure formation, decreasing the particle diameters, and the dispersibility of the particles. All of these factors were considerably affected by the Surf/Si ratio. The results suggested novel opportunities to control various colloidal mesostructured nanoparticles from the aspects of composition, structure, and morphology and will also be useful in the development of novel methods to prepare nanomaterials in various fields.

    Original languageEnglish
    Pages (from-to)3491-3500
    Number of pages10
    JournalACS Applied Materials and Interfaces
    Volume6
    Issue number5
    DOIs
    Publication statusPublished - 2014 Mar 12

    Fingerprint

    Cationic surfactants
    Silicon Dioxide
    Particle size
    Silica
    Surface-Active Agents
    Nanoparticles
    Surface active agents
    Micelles
    Drug delivery
    Nanostructured materials
    Catalysis
    Particles (particulate matter)
    Electrostatics
    Hydrolysis
    Nucleation
    Water
    Chemical analysis

    Keywords

    • dispersion
    • mesostructured silica nanoparticles
    • particle size
    • surfactants

    ASJC Scopus subject areas

    • Materials Science(all)

    Cite this

    Critical roles of cationic surfactants in the preparation of colloidal mesostructured silica nanoparticles : Control of mesostructure, particle size, and dispersion. / Yamada, Hironori; Urata, Chihiro; Higashitamori, Sayuri; Aoyama, Yuko; Yamauchi, Yusuke; Kuroda, Kazuyuki.

    In: ACS Applied Materials and Interfaces, Vol. 6, No. 5, 12.03.2014, p. 3491-3500.

    Research output: Contribution to journalArticle

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