Figure 2
From: Spontaneous patterning method utilizing transformation of UV-curable emulsion
Quantitative analysis of ET method. (A) Relationship between drying time after UV exposure and difference in height between UV-exposed and unexposed regions. The average particle size of the emulsion was 87.3 μm. The L/S sizes of the photomask are 2 mm/2 mm. The UV illuminance was 4.6 mW/cm2. The total exposure was 36.8 mJ/cm2. The pattern formed by the UV exposure of emulsion was dried at room temperature (23 ℃ 57%RH). The height difference of the pattern was obtained by measuring the 3D shape and cutting out the cross-sectional profile. (a) Optical micrograph 1 min after UV exposure was completed. (b,c) 15 and 45 min after exposure, respectively. (d) 3D images 1 min after UV exposure was completed. (e,f) 15 and 45 min after exposure, respectively. These 3D images are stretched three times in the depth direction to emphasize the stereoscopic effect. Error bars show SD. n = 6. (B) Cross-sectional SEM images of the UV-exposed portion of pattern cured by entire-surface UV irradiation for fixation. (a) 1 min after UV exposure was finished. (b–g) 5, 10, 15, 20, 30 and 45 min after UV exposure, respectively. (C) Relationship between the square root of drying time and remaining volume of the unexposed emulsion layer. The volume V of the unexposed emulsion layer was estimated using the exposed pattern area (A: 2 mm × B: 10 mm) and the average height C (refer to (A)) of the emulsion deposition layer in the unexposed portion. V = A × B × C. The average height of the exposed region was used as the reference for the height of the unexposed region. R2 = 0.984.
