Polymer-Assisted Self-Assembly of Superparamagnetic Iron Oxide Nanoparticles into Well-Defined Clusters: Controlling the Collective Magnetic Properties

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• 作者：Christian Schmidtke ; Robin Eggers ; Robert Zierold ; Artur Feld ; Hauke Kloust ; Christopher Wolter ; Johannes Ostermann ; Jan-Philip Merkl ; Theo Schotten ; Kornelius Nielsch ; Horst Weller
• 刊名：Langmuir
• 出版年：2014
• 出版时间：September 23, 2014
• 年：2014
• 卷：30
• 期：37
• 页码：11190-11196
• 全文大小：390K
• ISSN：1520-5827

文摘

The combination of superstructure-forming amphiphilic block copolymers and superparamagnetic iron oxide nanoparticles produces new nano/microcomposites with unique size-dependent properties. Herein, we demonstrate the controlled clustering of superparamagnetic iron oxide nanoparticles (SPIOs) ranging from discretely encapsulated SPIOs to giant clusters, containing hundreds or even more particles, using an amphiphilic polyisoprene-block-poly(ethylene glycol) diblock copolymer. Within these clusters, the SPIOs interact with each other and show new collective properties, neither obtainable with singly encapsulated nor with the bulk material. We observed cluster-size-dependent magnetic properties, influencing the blocking temperature, the magnetoviscosity of the liquid suspension, and the r₂ relaxivity for magnetic iron oxide nanoparticles. The clustering methodology can be expanded also to other nanoparticle materials [CdSe/CdS/ZnS core/shell/shell quantum dots (QDs), CdSe/CdS quantum dots/quantum rods (QDQRs), gold nanoparticles, and mixtures thereof].