title: Hollow magnetic microspheres obtained by nanoparticle adsorption on surfactant stabilized microbubbles.
abstract: We report on the stabilization of nanoparticle-decorated microbubbles for long periods of time using a synergism between a soluble surfactant and nanoparticles. The soluble surfactant is the perfluoroalkyl phosphate C8F17(CH2)2OP(O)(OH)2 (labeled F8H2Phos) and the nanoparticles (NPs) are 20-25 nm cobalt ferrite (CoFe2O4). The NP-F8H2Phos system has been studied by dynamic light scattering, dynamic magnetic susceptibility measurements and thermal gravimetric analysis. Microbubbles with diameters in the 1-20 μm range have been stabilized in 0.1 M NaCl brine. Its presence is crucial for the long-term stabilization. The surfactant adsorbs rapidly on bubbles and slows down the bubble shrinkage. Thus, the NPs can attach to the bubble and form a hollow sphere with a rigid shell. The charge screening by NaCl favors the attachment of NPs to the bubble surface. The coverage of the bubbles by the CoFe2O4 nanoparticle layer is confirmed by thermally induced inflation-deflation experiments and the control of bubbles with a magnetic field.
authors.affiliation: Institut Charles Sadron (ICS) CNRS - Université de Strasbourg (UPR 22), 23 rue du Loess, BP 84047, 67034 Strasbourg Cedex 2, France.
authors.forename: Artem
authors.initials: A
authors.lastname: Kovalenko
authors.forename: Julien
authors.initials: J
authors.lastname: Jouhannaud
authors.forename: Prasad
authors.initials: P
authors.lastname: Polavarapu
authors.forename: Marie Pierre
authors.initials: MP
authors.lastname: Krafft
authors.forename: Gilles
authors.initials: G
authors.lastname: Waton
authors.forename: Geneviève
authors.initials: G
authors.lastname: Pourroy
mesh_terms: D000327:Adsorption; D003035:Cobalt / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry; D005466:Fluorocarbons / Q000737:chemistry; D060526:Magnetic Fields; D053768:Metal Nanoparticles / Q000737:chemistry*; D008863:Microspheres; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
chemical_list: D005296:Ferrous Compounds; D005466:Fluorocarbons; D013501:Surface-Active Agents; D003035:Cobalt