Here we report production of super stable foams stabilized by rigid CaCO3 rods (diameter of 1.0μm, length of 25μm) modified by fatty acids. Foams stabilised by these rods are stable for several months and show a bi-modal bubble size distribution, mediated by the interplay between rigid rod length and bubble curvature. It was observed that for bubbles smaller than the rod length, rods are partially attached at the surface and order in nest-like structures; whilst for very large bubbles there is a monolayer of rods fully attached to the bubble surface, showing 2D well ordered nematic domains, resembling ordering of stiff rods on flat 2D surface. Larger armoured bubbles show improved resistance against added concentrated surfactant solutions, indicating that nest like structure is present in a kinetically trapped, meta-stable state.

We observe that small amounts (less than 1wt%) of ethanol can have a profound triggering effect on foamability. We demonstrate that this is due to a short range sticky interaction between the modified rods, due to conformational changes in the grafted fatty acid chains, whilst the wetting behaviour of the rods remains unchanged. This sticky interaction could be switched on and off by either changing the degree of saturation of the fatty acid chains or by the addition of small amounts of solvents or surfactants.

Due to their very high mechanical stability, rod-stabilized bubbles can be treated as solid particles and could be ordered and dried into packed 2D arrays on solid substrates, showing pronounced effects of bubble bi-modality, where big bubbles attach first, while small bubbles are filing the crevices in between. These 2D arrays of dried packed bubbles represent a hierarchy of self–assembled surfaces at different levels and types: at rod, at bubble and at solid substrate. This self assembly hierarchy spans more then 6 orders of magnitude: where a small changes in the degree of saturation at the Å level, has an effect on the self assembly of the fatty acids chains at rigid rods surface at nm level, which combined with rod topology then influences the interaction between the rods and their self assembly at the bubble surface at the micron level, thus determining the bubble size distribution at mm level, which in turn governs the bubble ordering and self assembly on solid substrates at the cm level.