Monolayers of soft microgels attract increasing attention due to their potential in the fabrication of tailored and responsive assemblies. Due to the fact that microgels are soft, deformable and partially penetrable makes them characteristically different from rigid colloidal particles.<br/>The interaction of pH-sensitive Poly (N-isopropylacrlyamide-co-methacrylic acid) microgels at oil water interfaces was investigated by means of compression isotherms in a Langmuir trough. Master curves were obtained at different pH-values. Surprisingly the microgels are easier to compress when they are in the charged as compared to the uncharged state. Thus the microgel-microgel interaction is not governed by direct Coulomb repulsion. This demonstrates the distinct differences of soft microgels as compared to rigid colloids.<br/><br/>The formation of ordered microgel structures on solid substrates is also of great interest. While the arrangement at the solid surface cannot be easily controlled after adsorption and self-assembly from the bulk phase, specific structures can be achieved by compressing a fluid interfacial microgel monolayer spread in a Langmuir trough and by transferring it onto substrates at distinct compression states. The degree of ordering after compression surpasses the one that is reached after self-assembly from the bulk and is, in general, independent from the presence of charges and different microgel morphologies. As a consequence, by monitoring the surface pressure during compression it is possible to produce highly ordered microgel arrays where the interparticle distance can be systematically and externally controlled.

Interactions and ordering of soft microgels at oil-water interfaces

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.