Dimethyl sulfoxide in a Langmuir trough

[Display omitted] •Stable surface layers of water-soluble dimethyl sulfoxide (DMSO) on water.•Poorly soluble multilayer films of DMSO on substrates.•Gibbs layers of DMSO compressed and transferred.•A new robust method and device for forming DMSO spread layers. Dimethyl sulfoxide (DMSO) is sometimes used as a solvent in the preparation of Langmuir-Blodgett (LB) films. By analogy with standard volatile solvents, it is often assumed that DMSO has no further effect once the solute molecules are distributed over the subphase surface. We hypothesized that this is not always the case and that DMSO may play an important role by remaining on the surface after spreading, contributing to the isotherms, influencing the formation of the LB film, and being incorporated into the resulting film. We studied the spreading of pure DMSO and the properties of Langmuir (spread) and Gibbs (adsorbed) layers of DMSO on water, proposed a robust approach to form the spread layers, and used the LB method to fabricate multilayer films on solid substrates. DMSO, which is completely miscible with water, can itself form a spreading surface layer very similar to the Langmuir layers of insoluble amphiphiles. When transferred repeatedly to a substrate, this layer forms a remarkably stable, poorly soluble multilayer film.