24 Biomimetic Functions by Microscopic Molecular Reactions …
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a height of 10 cm onto these surfaces for monitoring the bouncing phenomena. The
microcrystalline surface consists of only 1o forming a rough surface of larger needleshaped crystals shows water-adhesive properties as shown in Fig. 24.8g, whereas the
microcrystalline surface consists of only 3o forming a rough surface of smaller
needle-shaped crystals shows water-bouncing properties (Fig. 24.8i). We released
a water droplet to the surface B with two types of needle-shaped-crystals of 1c
and 3c in the same way and found a small portion of water remained on the surface
(Fig. 24.8h). On this surface in which needle-shaped crystals worked to provide either
water adhesion or repellency is a question. These results indicated that on surface B,
the longer needle-shaped crystal of 1c achieved water-capturing capability, whereas
the smaller needle-shaped crystals of 3c achieved water-repelling capability.
Then, we measured the sizes of all droplets contacting the surfaces. By comparing
the size distributions of the droplets, the bouncing and non-bouncing ranges are
separated by mixing the two diarylethenes.
On the surfaces of A and C, the difference between the average of the size
of a droplet showing bouncing and that showing non-bouncing behavior is relatively small, at 76.2 and 66.8 µm, respectively. On the other hand, this difference
for B was rather larger (155.1 µm). These results indicate that by mixing the two
diarylethene derivatives, the difference between bouncing and non-bouncing water
droplets became dramatically separated, i.e., the dependence on the size of water
droplets was clearly distinguished for both types of wettability (Fig. 24.9).
24.6 Object Transportation System Consists of Bending
Crystals
The design of an object transportation system exploiting the bending behavior of
surface-assembled diarylethene crystals is reported. Since Irie and his co-workers
reported the photoinduced bending behavior [4], photoinduced bending, rolling and
twisting [22], and elegant demonstration of an iron ball lifting and gear rotating
on a bending crystals [23, 24]. Herein, we design the array of bending crystals with
cooperative photoinduced bending to carry the object far from the UV incidence, just
like photo-actuated cilia of inspired paramecium aurelia (Fig. 24.10) [25]. Molecular
packing of 6o in the crystal is shown in Fig. 24.11. There are two conformers of
M- and P-helix molecules, and they are alternatively combined with intermolecular
hydrogen bonding along long axis (b-axis) of the crystal.
The crystal array of the bending crystals of 6o was prepared by sublimation;
however, direct sublimation of 6o to obtain an amorphous film of 6o with a nearly flat
surface with dotted microstructures whose average diameter and height were 0.30 µm
and 0.43 µm, respectively (Fig. 24.12a). Then the dotted surface was coated with
Au–Pd alloy by magnetron sputtering, and then the surface with the Au–Pd alloy was
used as a target substrate resulted in the accelerated growth of thin platelet crystals
of 6o on each of the dots on the glass substrate (Fig. 24.12b). The average length and
417
a height of 10 cm onto these surfaces for monitoring the bouncing phenomena. The
microcrystalline surface consists of only 1o forming a rough surface of larger needleshaped crystals shows water-adhesive properties as shown in Fig. 24.8g, whereas the
microcrystalline surface consists of only 3o forming a rough surface of smaller
needle-shaped crystals shows water-bouncing properties (Fig. 24.8i). We released
a water droplet to the surface B with two types of needle-shaped-crystals of 1c
and 3c in the same way and found a small portion of water remained on the surface
(Fig. 24.8h). On this surface in which needle-shaped crystals worked to provide either
water adhesion or repellency is a question. These results indicated that on surface B,
the longer needle-shaped crystal of 1c achieved water-capturing capability, whereas
the smaller needle-shaped crystals of 3c achieved water-repelling capability.
Then, we measured the sizes of all droplets contacting the surfaces. By comparing
the size distributions of the droplets, the bouncing and non-bouncing ranges are
separated by mixing the two diarylethenes.
On the surfaces of A and C, the difference between the average of the size
of a droplet showing bouncing and that showing non-bouncing behavior is relatively small, at 76.2 and 66.8 µm, respectively. On the other hand, this difference
for B was rather larger (155.1 µm). These results indicate that by mixing the two
diarylethene derivatives, the difference between bouncing and non-bouncing water
droplets became dramatically separated, i.e., the dependence on the size of water
droplets was clearly distinguished for both types of wettability (Fig. 24.9).
24.6 Object Transportation System Consists of Bending
Crystals
The design of an object transportation system exploiting the bending behavior of
surface-assembled diarylethene crystals is reported. Since Irie and his co-workers
reported the photoinduced bending behavior [4], photoinduced bending, rolling and
twisting [22], and elegant demonstration of an iron ball lifting and gear rotating
on a bending crystals [23, 24]. Herein, we design the array of bending crystals with
cooperative photoinduced bending to carry the object far from the UV incidence, just
like photo-actuated cilia of inspired paramecium aurelia (Fig. 24.10) [25]. Molecular
packing of 6o in the crystal is shown in Fig. 24.11. There are two conformers of
M- and P-helix molecules, and they are alternatively combined with intermolecular
hydrogen bonding along long axis (b-axis) of the crystal.
The crystal array of the bending crystals of 6o was prepared by sublimation;
however, direct sublimation of 6o to obtain an amorphous film of 6o with a nearly flat
surface with dotted microstructures whose average diameter and height were 0.30 µm
and 0.43 µm, respectively (Fig. 24.12a). Then the dotted surface was coated with
Au–Pd alloy by magnetron sputtering, and then the surface with the Au–Pd alloy was
used as a target substrate resulted in the accelerated growth of thin platelet crystals
of 6o on each of the dots on the glass substrate (Fig. 24.12b). The average length and