Measuring Bending Rigidity and Compression Resistance in Pickering Layers

ABSTRACT The mechanical properties of Pickering layers are crucial for stabilizing Pickering emulsions by resisting coalescence and deformation under mechanical stress. Despite the importance of mechanical properties in determining emulsion stability and functionality, these properties remain poorly understood in general. This study examines the buckling behavior and mechanical stability of Pickering layers made from 5 µm polystyrene beads (PBs) and clay particles (CPs) at the air–water interface. Controlled mechanical stresses were applied using a Langmuir trough (LT) and a magnetic force setup (MFS) to analyze response under compression. PB monolayers showed buckling at a range from 40 to 70 mN/m. Partial elastic recovery upon release of compression force was observed only in the LT, presumably due to boundary conditions. CP layers resisted compression through particle overlap and exhibited no buckling or elastic recovery, showing permanent deformation measured from 55 to 350 mN/m. A key contribution of this work is a novel method for measuring bending rigidity (BR) in Pickering layers. The results obtained from both experimental setups are remarkably consistent, revealing BR values higher than previous theoretical predictions. Additionally, the experimental buckling wavelength is found to be smaller than the predicted theoretical value. Practical Applications : This research supports the development of advanced materials with tailored mechanical properties, enabling applications like stabilizing emulsions and creating robust, responsive interfacial films. It also opens new opportunities for designing smart coatings that adapt to mechanical stress. For example, depending on environmental conditions, Pickering layers could be used in sensors and protective surfaces that require stability or flexibility. The insights into the mechanical properties of clay‐based Pickering layers and the resistance to deformations extend to cosmetics, where clays like kaolin and bentonite are valued for their absorbent and soothing properties, improving the design of stable and effective formulations like face masks and creams. Additionally, these findings could benefit industries requiring high‐pressure stability, such as environmental remediation, by enhancing the development of robust and durable materials. The novel method for quantifying BR also has potential for material characterization, aiding in the development of new particle‐stabilized systems for pharmaceuticals, cosmetics, or food science, where precise control of interfacial properties is crucial.