Natural materials achieve remarkable functionality using only simple chemical building blocks, relying on architectures that span multiple length scales.

A key feature of many biological systems is their hierarchical porosity, which guides fluid transport from large channels down to nanopores where water acts as a nanoscale working fluid. In such confined spaces, water displays distinct structural dynamics and interfacial behaviour that strongly influence mechanical, transport, and optical responses.

In my talk I will introduce a new class of sustainable water-driven materials whose active behaviour originates from the interplay between hierarchically porous solids and interfacial or nanoconfined water. These Blue Materials exploit water-mediated processes such as humidity-responsive actuation, capillarity-driven transport, and pore-structure controlled optical effects.

Their functionality is rooted in the precise design of their pore architecture, especially at the nanoscale where confined water governs dynamic material behaviour. Beyond emulating natural processes, these principles open pathways for harvesting electrical energy from environmental wetting-drying cycles or from triboelectric processes, offering a sustainable approach to energy “generation” with porous materials.