Elasticity permeability and buckling of aspirated polyacrylamide microgels

Soft, porous materials combine elasticity with fluid transport, yet how these properties interact to produce mechanical instabilities remains poorly understood. Here we use polyacrylamide microbeads and microcapsules as model of soft porous materials to investigate this coupling. By combining quantitative micropipette aspiration with scaling analysis, we establish a relationship between elastic modulus E and hydraulic permeability k , showing that both are governed by the network mesh size even in highly heterogeneous gels. In hollow microcapsules, we observe buckling instabilities within well-defined ranges of shell thickness and pipette radius. A model coupling shell elasticity to hydrodynamically driven deswelling accounts for these instabilities and reveals how solvent transport can trigger mechanical collapse. These results establish a direct link between network structure, fluid transport and mechanical instability, providing a framework for understanding similar phenomena in physical gels, biological vesicles and shell-coated condensates, with potential relevance to cellular mechanics, tissue engineering and adaptive materials.