Deposition of organized surfactant films on solid substrates

Abstract

Newton black films correspond to the ultimate stage of thinning of surfactant films and are molecularly assembled. The organization properties of surfactant molecules are widely used for ordering sufficiently small organic or inorganic objects. Examples are the Langmuir–Blodgett or the Langmuir–Schaefer methods. The resulting arrangements have a wide range of applications. But, so far, surfactant black films have been studied mainly in their fragile free-standing form. To render such films amenable to practical applications, it is therefore necessary to find ways of transfering them onto a solid substrate. In this paper, we present a method to transfer different surfactant bilayers onto a hydrophobic solid substrate. The transferred films cover a large surface area (a few cm 2) and X-ray reflectivity and atomic force microscopy prove that the organization of the film is preserved. This method can be applied to many kinds of surfactants. We show here results for a cationic surfactant (hexadecyltrimethylammonium bromide), a non-ionic surfactant (hexaethylene glycol monododecylether), and a fluorinated non-ionic surfactant. Moreover free-standing Newton black films have been proved to organize monolayers of large biological molecules with surfactants such as hexaethylene glycol monododecylether, phospholipids and fluorinated surfactants. Driving forces are either diffusion process or electrostatic forces. Combining the insertion and organization of bio-molecules or nanoparticles within the surfactant bilayers and the transfer of these architectures onto a solid substrate has a great potential for the formation of two- or even three-dimensional architectures of nanosized particle assemblies which have fundamental as well as practical applications.