Compression of colloidal monolayers at liquid interfaces: <i>in situ vs. ex situ</i> investigation.

Abstract

The assembly of colloidal particles at liquid/liquid or air/liquid interfaces is a versatile procedure to create microstructured monolayers and study their behavior under compression. When combined with soft and deformable particles such as microgels, compression is used to tune not only the interparticle distance but also the underlying microstructure of the monolayer. So far, the great majority of studies on microgel-laden interfaces are conducted <i>ex situ</i> after transfer to solid substrates, for example, <i>via</i> Langmuir-Blodgett deposition. This type of analysis relies on the stringent assumption that the microstructure is conserved during transfer and subsequent drying. In this work, we couple a Langmuir trough to a custom-built small-angle light scattering setup to monitor colloidal monolayers <i>in situ</i> during compression. By comparing the results with <i>ex situ</i> and <i>in situ</i> microscopy measurements, we conclude that Langmuir-Blodgett deposition can alter the structural properties of the colloidal monolayers significantly.