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Short notice given only substantially as follows: Nacre or mother of pearl is a paradigm for structural high-performance layered nanocomposite due to its notable combination of stiffness (40-70 GPa), strength (80-135 MPa), and toughness (3000 times higher than aragonite monolith) originating from the complex hierarchical arrangement of reinforcing CaCO3 platelets (95 vol%) nicely aligned within the energy-dissipating biopolymer matrix in an alternating hard and soft manner. Its unique mechanical properties therefore fascinate us to mimic nacre. Herein, we will present water-borne large-scale self-assembly approaches to prepare nacre-mimetics from bio-based as well as synthetic components. We mimic nacre via self-assembly of polymer-coated nanoclay platelets with intrinsic hard/soft character to fabricate films or coatings with highly defined and tunable mesostructure. We obtained ultrastiff (40 GPa) and strong (320 MPa) materials combined with low density and synergistic mechanical properties at high humidity by supramolecular crosslinking. Further we will show how nanostructure formation and deformation mechanisms of nacre-mimetics are influenced as a function of aspect ratio of nanoclays, thickness of organic layers and by tuning viscoelastic properties of the soft phase at different level of hydration. Functional properties e.g. glass-like transparency, high gas barrier, printability and fire/heat shielding capabilities displayed by these materials open avenues for flexible and advanced barrier materials.