In situ imaging of the three-dimensional shape of soft responsive particles at fluid interfaces by atomic force microscopy

The reconfiguration of individual soft and deformable particles upon adsorption at a fluid interface underpins many aspects of their dynamics and interactions, ultimately regulating the properties of monolayers of relevance for applications. In this work, we demonstrate that atomic force microscopy can be used for the in situ reconstruction of the three-dimensional conformation of model poly(N-isopropylacrylamide) microgels adsorbed at an oil-water interface. We image the particle topography from both sides of the interface to characterize its in-plane deformation and to visualize the occurrence of asymmetric swelling in the two fluids. In addition, the technique enables investigating different fluid phases and particle architectures, as well as studying the effect of temperature variations on particle conformation in situ. We envisage that these results open up an exciting range of possibilities to provide microscopic insights into the single-particle behavior of soft objects at fluid interfaces and into the resulting macroscopic material properties.

Automated summary

In this work, we demonstrate the in situ reconstruction of the three-dimensional conformation of microgels adsorbed at an oil-water interface using atomic force microscopy. The technique allows for characterization of in-plane deformation and visualization of asymmetric swelling in the two fluids. It also enables the investigation of different fluid phases, particle architectures, and temperature variations on particle conformation. These results provide microscopic insights into single-particle behavior of soft objects at fluid interfaces and their resulting macroscopic material properties.