Long Nanofibers Arrays Through Surfactant Self-Assembly

Abstract

Self assembly of molecules can be a simple and versatile approach that may lead to nanostructures. Here we report the formation of arrangements of exceptionally long nanofibers of cationic surfactant hexadecyltrimethylammonium bromide molecules with highly defined spatial and parallel ordering. Arrangements of approximately 1 microm long nanofibers were observed by non-contact atomic force microscopy. The long nanofiber patterns form structures in approximately 5 x 5 microm2 regions and consist of approximately 6 nm wide lines. The formation mechanism of the fibers is shown to be the coalescence of isolated surfactant micelles (approximately 3.2 nm diameter in solution) in the convection stream of the surfactant solution drop close to the pinned contact-line region during drying. The size of micelles formed in solution determines the diameter of the deposited fibers. New deposition schemes of micelles forming nanorods on bare silicon previous to the formation of surfactant bilayers are now being investigated based on the data obtained in this work.