Cobalt nanoparticles formed in polysiloxane copolymer micelles: Effect of production methods on magnetic properties

Joan Connolly, Tim St Pierre, M. Rutnakornpituk, J.S. Riffle

    Research output: Contribution to journalArticle

    27 Citations (Scopus)

    Abstract

    The effect of production method on the chemical and magnetic stability of a range of cobalt nanoparticles formed in polysiloxane copolymer micelles was studied. The nanoparticles were suspended in polydimethylsiloxane (PDMS) carrier fluids and are prototypes for use in biomedical applications. Three families of particles were investigated: cobalt particles in triblock copolymer micelles and silica-coated cobalt particles where the silica coating is formed either in toluene or PDMS carrier fluid. The silica coating effectively protects the cobalt particles from ongoing oxidation, with little change in the saturation magnetization of the particles observed over time and only a small shift in the centre of the field-cooled hysteresis loop observed. Temperature-dependent magnetization measurements show that the silica-coated particles have superparamagnetic blocking temperatures of 100–130 K compared with the non-silica-coated particles, which do not reach their characteristic blocking temperature below the melting point of the frozen fluids. This result is interpreted as a smaller magnetic core size in the silica-coated particles. The zero-field-cooled temperature-dependent magnetization of the silica-coated particles has two apparent superparamagnetic blocking temperatures, with a second, lower blocking temperature of approximately 15 K. This second apparent blocking temperature may be due to unreacted cobalt clusters in the suspensions or, alternatively, due to surface states on the nanoscale cobalt particles. The prototype silica-coated cobalt particles show promise for potential biomedical applications.
    Original languageEnglish
    Pages (from-to)2475-2482
    JournalJournal of Physics D: Applied Physics
    Volume37
    Issue number18
    DOIs
    Publication statusPublished - 2004

    Fingerprint

    Siloxanes
    production engineering
    polysiloxanes
    Micelles
    Cobalt
    Silicon Dioxide
    Silicones
    micelles
    Magnetic properties
    copolymers
    cobalt
    Copolymers
    Silica
    Nanoparticles
    magnetic properties
    nanoparticles
    silicon dioxide
    Particles (particulate matter)
    Temperature
    Polydimethylsiloxane

    Cite this

    @article{1abd79ed2db0484db20707a7b676e88d,
    title = "Cobalt nanoparticles formed in polysiloxane copolymer micelles: Effect of production methods on magnetic properties",
    abstract = "The effect of production method on the chemical and magnetic stability of a range of cobalt nanoparticles formed in polysiloxane copolymer micelles was studied. The nanoparticles were suspended in polydimethylsiloxane (PDMS) carrier fluids and are prototypes for use in biomedical applications. Three families of particles were investigated: cobalt particles in triblock copolymer micelles and silica-coated cobalt particles where the silica coating is formed either in toluene or PDMS carrier fluid. The silica coating effectively protects the cobalt particles from ongoing oxidation, with little change in the saturation magnetization of the particles observed over time and only a small shift in the centre of the field-cooled hysteresis loop observed. Temperature-dependent magnetization measurements show that the silica-coated particles have superparamagnetic blocking temperatures of 100–130 K compared with the non-silica-coated particles, which do not reach their characteristic blocking temperature below the melting point of the frozen fluids. This result is interpreted as a smaller magnetic core size in the silica-coated particles. The zero-field-cooled temperature-dependent magnetization of the silica-coated particles has two apparent superparamagnetic blocking temperatures, with a second, lower blocking temperature of approximately 15 K. This second apparent blocking temperature may be due to unreacted cobalt clusters in the suspensions or, alternatively, due to surface states on the nanoscale cobalt particles. The prototype silica-coated cobalt particles show promise for potential biomedical applications.",
    author = "Joan Connolly and {St Pierre}, Tim and M. Rutnakornpituk and J.S. Riffle",
    year = "2004",
    doi = "10.1088/0022-3727/37/18/002",
    language = "English",
    volume = "37",
    pages = "2475--2482",
    journal = "Journal of Physics D-Applied Physics",
    issn = "0022-3727",
    publisher = "IOP Publishing",
    number = "18",

    }

    Cobalt nanoparticles formed in polysiloxane copolymer micelles: Effect of production methods on magnetic properties. / Connolly, Joan; St Pierre, Tim; Rutnakornpituk, M.; Riffle, J.S.

    In: Journal of Physics D: Applied Physics, Vol. 37, No. 18, 2004, p. 2475-2482.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Cobalt nanoparticles formed in polysiloxane copolymer micelles: Effect of production methods on magnetic properties

    AU - Connolly, Joan

    AU - St Pierre, Tim

    AU - Rutnakornpituk, M.

    AU - Riffle, J.S.

    PY - 2004

    Y1 - 2004

    N2 - The effect of production method on the chemical and magnetic stability of a range of cobalt nanoparticles formed in polysiloxane copolymer micelles was studied. The nanoparticles were suspended in polydimethylsiloxane (PDMS) carrier fluids and are prototypes for use in biomedical applications. Three families of particles were investigated: cobalt particles in triblock copolymer micelles and silica-coated cobalt particles where the silica coating is formed either in toluene or PDMS carrier fluid. The silica coating effectively protects the cobalt particles from ongoing oxidation, with little change in the saturation magnetization of the particles observed over time and only a small shift in the centre of the field-cooled hysteresis loop observed. Temperature-dependent magnetization measurements show that the silica-coated particles have superparamagnetic blocking temperatures of 100–130 K compared with the non-silica-coated particles, which do not reach their characteristic blocking temperature below the melting point of the frozen fluids. This result is interpreted as a smaller magnetic core size in the silica-coated particles. The zero-field-cooled temperature-dependent magnetization of the silica-coated particles has two apparent superparamagnetic blocking temperatures, with a second, lower blocking temperature of approximately 15 K. This second apparent blocking temperature may be due to unreacted cobalt clusters in the suspensions or, alternatively, due to surface states on the nanoscale cobalt particles. The prototype silica-coated cobalt particles show promise for potential biomedical applications.

    AB - The effect of production method on the chemical and magnetic stability of a range of cobalt nanoparticles formed in polysiloxane copolymer micelles was studied. The nanoparticles were suspended in polydimethylsiloxane (PDMS) carrier fluids and are prototypes for use in biomedical applications. Three families of particles were investigated: cobalt particles in triblock copolymer micelles and silica-coated cobalt particles where the silica coating is formed either in toluene or PDMS carrier fluid. The silica coating effectively protects the cobalt particles from ongoing oxidation, with little change in the saturation magnetization of the particles observed over time and only a small shift in the centre of the field-cooled hysteresis loop observed. Temperature-dependent magnetization measurements show that the silica-coated particles have superparamagnetic blocking temperatures of 100–130 K compared with the non-silica-coated particles, which do not reach their characteristic blocking temperature below the melting point of the frozen fluids. This result is interpreted as a smaller magnetic core size in the silica-coated particles. The zero-field-cooled temperature-dependent magnetization of the silica-coated particles has two apparent superparamagnetic blocking temperatures, with a second, lower blocking temperature of approximately 15 K. This second apparent blocking temperature may be due to unreacted cobalt clusters in the suspensions or, alternatively, due to surface states on the nanoscale cobalt particles. The prototype silica-coated cobalt particles show promise for potential biomedical applications.

    U2 - 10.1088/0022-3727/37/18/002

    DO - 10.1088/0022-3727/37/18/002

    M3 - Article

    VL - 37

    SP - 2475

    EP - 2482

    JO - Journal of Physics D-Applied Physics

    JF - Journal of Physics D-Applied Physics

    SN - 0022-3727

    IS - 18

    ER -