Bio‐Mimicked Silica Architectures Capture Geometry, Microstructure, and Mechanical Properties of Marine Diatoms

The authors create life‐sized synthetic replicas of marine diatom coscinodiscus sp frustules out of cyclohexyl polyhedral oligomeric silsesquioxanes (POSS). The authors demonstrate that these synthetic structures have biosilica‐like amorphous atomic‐level microstructure and mechanical attributes similar to those of a natural diatom. In situ beam bending and fracture experiments on micron‐sized excised sections of natural and synthetic diatoms reveal similarities in their mechanical properties: a Young's modulus of 20.2 ± 2.6 GPa and a fracture toughness of 0.78 ± 0.10 MPa m^(−1/2) for the synthetic materials; those of natural diatoms are 36.4 ± 8.3 GPa and 1.05 ± 0.08 MPa mm^(−1/2), respectively. In situ single edge notched beam (SENB) bending fracture experiments reveal that fracture behavior of the natural and synthetic specimens is virtually indistinguishable and is characterized by the same brittle failure and crack‐arresting behavior enabled by the double‐wall geometry. Their fracture toughness is comparable to that of fully dense silica, which suggests that the natural diatoms’ frustule maintains its mechanical resilience even at