title: Crystallization at Nanodroplet Interfaces in Emulsion Systems: A Soft-Template Strategy for Preparing Porous and Hollow Nanoparticles.
abstract: A heterophase method to prepare hollow and/or porous crystalline nanoparticles of metal oxides at room temperature is presented, taking cerium(IV) oxide and γ-iron(III) oxide (i.e., maghemite) as representative cases. The crystallization begins at the oil-water interface in aqueous nanodroplets of the precursor in inverse (water-in-oil) miniemulsion systems, and it may continue toward the inner part of the droplets. A poly(styrene-b-acrylic acid) block copolymer is used as a structuring agent because the ability of the carboxylic groups to bind metal ions improves the inorganic shell formation. A precipitating base is added from the continuous phase, generating hydroxide species at the interface that begin the crystallization. We analyze the effects of the synthetic parameters in terms of colloidal stability and morphology of the resulting materials. In the case of maghemite samples, the prepared dispersions of hollow particles present a distinct magnetofluidic behavior.
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: H Samet
authors.initials: HS
authors.lastname: Varol
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.|Institut de Ciència dels Materials, Universitat de València , carrer Catedràtic José Beltrán 2, Paterna, 46980 València, Spain.
authors.forename: Olaia
authors.initials: O
authors.lastname: Álvarez-Bermúdez
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova , Via Marzolo 1, 35131 Padova, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Dolcet
authors.affiliation: Institut für Mikro- und Nanomaterialien, Universität Ulm , Albert-Einstein-Allee 47, 89081 Ulm, Germany.
authors.forename: Barat
authors.initials: B
authors.lastname: Achinuq
authors.affiliation: Dipartimento di Scienze Chimiche, Università degli Studi di Padova , Via Marzolo 1, 35131 Padova, Italy.|Istituto di Chimica della Materia Condensata e di Tecnologie per l'Energia - CNR (ICMATE-CNR) , Via Marzolo 1, 35131 Padova, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Gross
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Landfester
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.|Institut de Ciència dels Materials, Universitat de València , carrer Catedràtic José Beltrán 2, Paterna, 46980 València, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Muñoz-Espí