|
STRUCTURE-FUNCTION
RELATIONSHIPS IN BIOLOGICAL GLASS FIBERS
Recent interest in the optical and mechanical properties of silica
skeletal structures (spicules) made by living sponges, and the possibility
of harnessing these mechanisms for the synthesis of advanced materials
and devices, motivate our investigation of the micro- and nanoscale
architecture of these remarkable biological materials. High resolution
scanning electron and atomic force microscopic analyses of spicules
isolated from five different sponge species reveals an unanticipated
diversity of structural complexity characteristic of these unique
skeletal systems. All spicules, measuring greater than a few mm
in total length, exhibit a unique laminated architecture consisting
of alternating layers of hydrated amorphous silica and organic that
effectively halts crack propagation through these materials. In
spicules that experience stresses not confined to a single axis
(e.g. the anchor spicules from Euplectella aspergillum), there is
a reduction in silica layer thickness as one travels from the spicule
core to its periphery. In contrast, spicules that experience uniaxial
loading exhibit a discrete graded architecture with the thickest
silica layers found in regions of maximum compression and the thinnest
layers in regions of maximum tension. Basic design principles learned
from these studies are presented and may prove useful in a wide
range of technologically-important applications including the design
of more fracture-resistant optical fibers.
*final presentation
unavailable
Return
to Projects Page
|
