units (tier 2) along the c axis (Fig. 6.9d), although the orientation of the a and b axes
in a layer remains unclear. The mineral-bridges model of Schaeffer et al. implies
that the a and b axes should be perfectly oriented in all the layers in tier 1. However,
Dai and Sarikaya reported dark-field TEM images showing that the a and b axes
were not perfectly aligned in all the layers. XRD analysis indicates that the layers
are perpendicular to the c axis. Consequently, the oriented assembly of the plates
(tier 2) in the c axis make up the layered structure (tier 1). A single unit (tier 2) is
also an oriented assembly of nanobuilding blocks (tier 3). Aggregations of the
nanobuilding blocks showed that the nacreous layer is a three-level hierarchical
architecture associated with two forms of oriented assembly (Fig. 6.9). Electron
microscope analysis determined the morphology of the nanobuilding blocks and
their oriented assembly into platy units.
These results indicate that the aragonite–biopolymer composite behaves as a
host for organic molecules. Oaki and Imai (2005) have called this property
“nanostorage.” To gain a more comprehensive understanding of the superstructures, Oaki and Imai (2005) showed the detailed structures of two hierarchical
architectures that have “nanostorage” properties, and they discussed the mutual
growth process associated with the two respective roles of each polymer. The
results imply that the manipulation of crystals and polymers could lead to a novel
type of excellent inorganic–organic hybrid composites under ambient conditions.
They concluded that the unit, like the nacreous layer, is an oriented assembly of
nanobuilding blocks. They have elucidated the hierarchical architecture in nacre
and identified its ability to host organic molecules. This model case suggests that a
hierarchy similar to that of nacre can be induced through an appropriate combination of inorganic crystals and organic polymers. The specific interaction of the two
components generates the nanoscopic architecture, and the switching between the
modes of growth leads to the formation of macroscopic structure. Furthermore, an
improved understanding of real and mimetic biominerals holds promise for the
further development of chemical, biological, and materials sciences.
Storage, an additional nanoscopic function leading to the incorporation of
versatile organic dye molecules, is attributed to the aragonite–biopolymer
nanohybrid. The results are beneficial to the understanding of the overall architecture in the nacreous layer from the nanoscopic to the macroscopic scale.
6.2.3 Lackluster Pearl
Normal pearl is formed by nacre, which has attracted much attention because of its
complex architectures, superior mechanism properties, and applications in
materials design. Nacre inspires bright luster due to its regular structure layers of
uniformly thick tablets of aragonite and high mechanical performance thanks to the
organic matrix lying between neighboring tablets and lamellae to form a “brick and
mortar” structure. Much research has revealed that the aragonite tablets in nacre
have a strong texture basically with their c-axis perpendicular to the tablet plane,
160
Q. Feng
in a layer remains unclear. The mineral-bridges model of Schaeffer et al. implies
that the a and b axes should be perfectly oriented in all the layers in tier 1. However,
Dai and Sarikaya reported dark-field TEM images showing that the a and b axes
were not perfectly aligned in all the layers. XRD analysis indicates that the layers
are perpendicular to the c axis. Consequently, the oriented assembly of the plates
(tier 2) in the c axis make up the layered structure (tier 1). A single unit (tier 2) is
also an oriented assembly of nanobuilding blocks (tier 3). Aggregations of the
nanobuilding blocks showed that the nacreous layer is a three-level hierarchical
architecture associated with two forms of oriented assembly (Fig. 6.9). Electron
microscope analysis determined the morphology of the nanobuilding blocks and
their oriented assembly into platy units.
These results indicate that the aragonite–biopolymer composite behaves as a
host for organic molecules. Oaki and Imai (2005) have called this property
“nanostorage.” To gain a more comprehensive understanding of the superstructures, Oaki and Imai (2005) showed the detailed structures of two hierarchical
architectures that have “nanostorage” properties, and they discussed the mutual
growth process associated with the two respective roles of each polymer. The
results imply that the manipulation of crystals and polymers could lead to a novel
type of excellent inorganic–organic hybrid composites under ambient conditions.
They concluded that the unit, like the nacreous layer, is an oriented assembly of
nanobuilding blocks. They have elucidated the hierarchical architecture in nacre
and identified its ability to host organic molecules. This model case suggests that a
hierarchy similar to that of nacre can be induced through an appropriate combination of inorganic crystals and organic polymers. The specific interaction of the two
components generates the nanoscopic architecture, and the switching between the
modes of growth leads to the formation of macroscopic structure. Furthermore, an
improved understanding of real and mimetic biominerals holds promise for the
further development of chemical, biological, and materials sciences.
Storage, an additional nanoscopic function leading to the incorporation of
versatile organic dye molecules, is attributed to the aragonite–biopolymer
nanohybrid. The results are beneficial to the understanding of the overall architecture in the nacreous layer from the nanoscopic to the macroscopic scale.
6.2.3 Lackluster Pearl
Normal pearl is formed by nacre, which has attracted much attention because of its
complex architectures, superior mechanism properties, and applications in
materials design. Nacre inspires bright luster due to its regular structure layers of
uniformly thick tablets of aragonite and high mechanical performance thanks to the
organic matrix lying between neighboring tablets and lamellae to form a “brick and
mortar” structure. Much research has revealed that the aragonite tablets in nacre
have a strong texture basically with their c-axis perpendicular to the tablet plane,
160
Q. Feng