Langmuir–Blodgett assembly of bent-shaped rigid amphiphiles into spiral rings

Abstract

We report here the interfacial behaviour and structure of the Langmuir–Blodgett films of a series of bent-shaped rigid amphiphiles. Molecule 1, based on a shortest oligo(propylene oxide) chain, spontaneously aggregated into short cylinders at the air–water interface. Molecules 2 and 3 formed uniform monolayers at very low surface pressure. Upon compression nanorods appeared. Interestingly, these nanorods self-assemble into spiral rings nanostructures. High-resolution AFM images and UV-vis spectra with polarized light indicate that the nanorods, with a width of 5–8 nm and a length of 10–50 nm, were packed by 2–10 molecules via the π–π interaction of the rigid bent-core lying flat on the substrate. The spiral ring morphologies can be realized through a molecular design and a lateral compression. We suggested that the unusual spiral morphologies are associated with the peculiar rigid bent-shaped core and interfacial molecular interactions, such as capillary force and van der Waals attraction.