Monolayer formed by l-Asp-based gemini surfactants self-assembled in 1D nanostructures

Abstract

Herein, studies on the surface activities of newly synthesized L-Asp-based gemini surfactants, both nonionic and anionic, are presented. Conductometry, tensiometry, and the Langmuir–Blodgett (LB) film technique were applied for this purpose. π–A isotherms were obtained with a Langmuir trough and Wilhelmy balance. The structures of the monolayers assembled at the air/water interface and those deposited as LB films were studied via Brewster angle microscopy (BAM) and atomic force microscopy (AFM). The 2D films formed by the anion-active compounds show a well-known pattern of a monolayer film, whereas the nonionogenic amphiphiles have been found to be 1D structures with nano-widths and micro-lengths that align with each other during the process of compression; this is the first study where the organization of 1D fibrils in 2D films during compression is reported. The scanning electron microscopy (SEM) study reveals that 1D nanostructure formation is an intrinsic tendency of these molecules as not only nonionogenic surfactants, but also the anion active representatives have been constructed in the solid state by fibrillary structures.