RESEARCH PAPER The use of colloidal ferrofluid as building blocks for nanostructured layer-by-layer films fabrication A. Pereira • S. Alves • M. Casanova • V. Zucolotto • I. H. Bechtold Received: 18 August 2009 / Accepted: 7 January 2010 / Published online: 20 January 2010 Ó Springer Science+Business Media B.V. 2010 Abstract The electrostatic layer-by-layer technique has been exploited as an useful strategy for fabrication of nanostructured thin films, in which specific prop- erties can be controlled at the molecular level. Ferrofluids consist of a colloidal suspension of magnetic grains (with only a few nanometers of diameter) with present interesting physical properties and applications, ranging from telecommunication to drug delivery systems. In this article, we developed a new strategy to manipulate ferrofluids upon their immobilization in nanostructured layered films in conjunction with conventional polyelectrolytes using the layer-by-layer technique. We investigated the morphological, optical, and magnetic properties of the immobilized ferrofluid as a function of number of bilayers presented in the films. Ferrofluid/polyelec- trolyte multilayers homogeneously covered the sub- strates surface, and the magnetic and optical properties of films exhibited a linear dependence on the number of bilayers adsorbed. Keywords Ferrofluid  Layer-by-layer technique  Nanostructured film  Magnetic particles  Nanomanufacturing Introduction The electrostatic layer-by-layer (LbL) technique has been widely exploited as a simple and efficient tool for assembling nanostructured thin films (Decher 1997; Ji et al. 2009; Ariga et al. 2007; Siqueira et al. 2006) and materials (de Geest et al. 2007; Wang et al. 2008; Ariga et al. 2008), in which control over specific properties may occur at the molecular level. The LbL technique consists of adsorption of ionic molecules onto a substrate leading to well-organized films with a precise control of the thickness. This technique is of special interest in cases where conjugation of different materials is required, since the interactions between the multilayers are maxi- mized due to the nanostructured architecture of the films. The latter concept has allowed the fabrication of thin films containing a variety of materials, including polymers (Huguenin et al. 2005), azopoly- mers (Zucolotto et al. 2004), nanoparticles (He et al. 1999; Crespilho et al. 2006), biomolecules, (Lvov et al. 1995; Onda et al. 1997), which found applica- tions in optical storage (Fou et al. 1996; Oliveira et al. A. Pereira  I. H. Bechtold (&) Departamento de Fı ´sica, Universidade Federal de Santa Catarina, Floriano ´polis, SC 88040-900, Brazil e-mail: bechtold@fsc.ufsc.br S. Alves Departamento de Cie ˆncias Exatas e da Terra de Fı ´sica, Universidade Federal de Sa ˜o Paulo, Diadema, SP 09972-270, Brazil M. Casanova  V. Zucolotto Instituto de Fı ´sica de Sa ˜o Carlos, Universidade de Sa ˜o Paulo, P.O. Box 369, Sa ˜o Carlos, SP 13560-970, Brazil 123 J Nanopart Res (2010) 12:2779–2785 DOI 10.1007/s11051-010-9855-z