Lamellar architectures in stiff biomaterials may not always be templates for enhancing toughness in composites

Abstract

The layered architecture of stiff biological materials often endows them with surprisingly high fracture toughness in spite of their brittle ceramic constituents. Understanding the link between organic-inorganic layered architectures and toughness could help to identify new ways to improve the toughness of biomimetic engineering composites. We study the cylindrically layered architecture found in the spicules of the marine sponge Euplectella aspergillum. We cut micrometer-size notches in the spicules and measure their initiation toughness and average crack growth resistance using flexural tests. We find that while the spicule's architecture provides toughness enhancements, these enhancements are relatively small compared to prototypically tough biological materials, like nacre. We investigate these modest toughness enhancements using computational fracture mechanics simulations.

Modern scaffolding strategies based on naturally pre-fabricated 3D biomaterials of poriferan origin

“…Numerous studies of glass sponges skeletons suggest that the unique fracture toughness results from the spicules cylindrical layered architecture. However, Monn et al [18] discovered that while interfacial fracture does improve the toughness of the cylindrically layered beam, its impact is relatively small compared to the arrest and re-nucleation mechanism that occurs in the planar layered beam [18]. This finding is questioning this theory and shows that the understanding of the relationship between layered architectures and toughness enhancement is not yet complete.…”

“…1 Sponges possess a unique ability to produce hierarchically structured 3D scaffolds made of chitin, spongin, or silica-based biocomposites of both biopolymers. Due to the cultivation of sponges, they represent a unique renewable source of such 3D constructs of novel materials [21,22], by means of existing tools and manufacturing schemes, for the targeted application in new 3D open-celled products to be used for human endeavors [13,18]. Over the last decades numerous research groups analyzed the organic constituents involved in spiculogenesis and supporting formation of sophisticated glass sponge constructs.…”

Mechanical and hydrodynamic analyses of helical strake-like ridges in a glass sponge

“…First, single-spicule studies have revealed the presence of an underlying laminated architecture consisting of concentric lamellae of consolidated silica nanoparticles separated by thin organic interlayers. The silica layers decrease in thickness from the spicule core to its periphery, resulting in a functionally graded design that effectively retards crack propagation through the spicules, while simultaneously increasing their buckling resistance [3,6].…”

Synthesis of self-assembled nacre-like materials with 3D periodic layers from nanochitin via hydrogelation and mineralization

“…Biogenic materials usually exceed the mechanical performance achievable by man-made counterparts, even if built from similar components. This justi es the ongoing quest to approach biomimicry as a design process to achieve such performance, [1][2][3][4][5][6] which has considered biomineralization and other mechanisms. In the animal kingdom, such processes lead to the formation of bones, enamel and cuticles, among others.…”