24 Biomimetic Functions by Microscopic Molecular Reactions …
409
above T g . Then, we monitored the crystal growth 1c, 2c, 3c, and 4c on the microcrystalline surfaces of the open-ring isomers above T g , where the T g of 1o, 2o, 3o, and
4o are −13.0, 27.9, 31.3, and 24.7 °C, respectively. The shapes of photogenerated
crystals of their derivatives are needles for 1c and 3c, cubic for 2c, and plates for 4c
as shown in Fig. 24.3 [8]. They are attributed the crystal structure of the closed-ring
Fig. 24.3 SEM images of the diarylethene microcrystalline surfaces after UV irradiation followed
by storage in the dark. a–c: surface of 1o, d–f: surface of 2o, g–i surface of 3o, and j–l surface
of 4o. a, d, g, and j Stored at the eutectic temperature of the mixture of the open- and closed-ring
isomers. b, e, h, and k Stored at the T g or at the temperature above the T g and below the eutectic
temperatures, which are indicated below for each case. c, f, i, and l Stored at the temperature below
the T g . a Stored at 30 °C for 15 h, b stored at 8 °C which is above the T g and below the eutectic
temperature for 48 h, c stored at–30 °C for 1 week, d Stored at 120 °C for 24 h, e stored at 30 °C of
the T g for 72 h, f stored at 8 °C for 1 week, g stored at 141 °C for 20 min, h stored at 30 °C of the
T g for 12 h, i stored at 8 °C for 7 days, j stored at 100 °C for 3 h, k stored at 80 °C which is above
the T g for 48 h, l stored at 8 °C for 7 days. Magnitude: a, b, c, i: ×3000, d, e, f: ×1000; g ×2000;
h ×7000; j, k ×1000, l: ×3000