"Surfaces play a crucial role in the interaction of a material with its environment. Recent advances in Soft Matter physics reveal the extraordinary properties of surfaces with complex physico-chemical modifications. Of particular interest is the influence of such modifications on the wetting and flow of simple or complex fluids. Despite growing research efforts, a sound understanding and large-scale applications remain out of reach due to the difficulty of creating complex surfaces with satisfying control and cost. In particular, no technique exists to reliably modify surfaces within complex materials, like micro-porous solids.I therefore propose to develop an original bottom-up approach which relies on the self-organisation of interfacially active agents (polymers, particles) at the interface between two fluids. Using microfluidic techniques and the self-ordering of equal-volume drops under gravity, I will create highly periodic emulsions from these fluids which are stabilised by one type of agent. Solidification of the continuous phase (including the agent) and removal of the discrete phase will lead to the creation of a micro-porous solid with well-defined morphology to which the agent confers the desired surface modification (polymer brush, surface roughness).In systematically comparing the properties of these porous solids with those of flat modified surfaces, I aim to solidly correlate their surface properties with the resulting wetting/flow properties of simple and complex fluids. Building on this understanding and the acquired technical knowhow I aim to realise two long-sought applications: a supersponge & a liquid spring.To establish my research group as a world leader in this rapidly evolving and competitive domain at the interface between physics and chemistry, I need to tackle this project at different length scales and levels of complexity with a long term vision. At my career stage only an ERC Starting Grant can provide me with this possibility"