TY - JOUR
T1 - Precursor-Film-Mediated Thermocapillary Motion of Low-Surface-Tension Microdroplets
AU - Teshima, Hideaki
AU - Misra, Sirshendu
AU - Takahashi, Koji
AU - Mitra, Sushanta K.
N1 - Funding Information:
This work was partially supported by S.K.M.’s Discovery Grant (RGPIN-2019-04060) from Natural Sciences and Engineering Research Council (NSERC), Canada, and by K.T.’s JST CREST Grant No. JPMJCR18I1 and by H.T.’s Grant-in-Aid for JSPS Research Fellow No. JP18J11880, Japan. S.M. additionally acknowledges financial support from Waterloo Institute for Nanotechnology, University of Waterloo in the form of Nanofellowship 2018. We thank Dr. Kiran Raj M for support with surface profilometry. We also thankfully acknowledge Dr. Enrique Wagemann for helpful scientific discussion, Yuko Nishizawa for valuable suggestion about the asymmetric quadratic function, and Dr. Mizuki Tenjimbayashi for helpful suggestions during designing the 3D cover art.
Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/5/19
Y1 - 2020/5/19
N2 - In contrast to microdroplet condensation with high contact angles, the one with low contact angles remains unclear. In this study, we investigated dynamics of microdroplet condensation of low-surface-tension liquids on two flat substrate surfaces by using reflection interference confocal microscopy. Spontaneous migration toward relatively larger droplets was first observed for the microdroplets nucleated on the hydrophilic quartz surface. The moving microdroplets showed a contact angle hysteresis of a0.5°, which is much lower than the values observed on typical flat substrates and is within the range observed on slippery lubricant-infused porous surfaces. Because the microdroplets on the hydrophobic polydimethylsiloxane surface did not move, we concluded that the ultrathin precursor film is formed only on the hydrophilic surface, which reduces a resistive force to migration. Also, reduced size of droplets promotes the thermocapillary motion, which is induced by a gradient in local temperature inside a small microdroplet arising due to the difference in size of adjacent droplets.
AB - In contrast to microdroplet condensation with high contact angles, the one with low contact angles remains unclear. In this study, we investigated dynamics of microdroplet condensation of low-surface-tension liquids on two flat substrate surfaces by using reflection interference confocal microscopy. Spontaneous migration toward relatively larger droplets was first observed for the microdroplets nucleated on the hydrophilic quartz surface. The moving microdroplets showed a contact angle hysteresis of a0.5°, which is much lower than the values observed on typical flat substrates and is within the range observed on slippery lubricant-infused porous surfaces. Because the microdroplets on the hydrophobic polydimethylsiloxane surface did not move, we concluded that the ultrathin precursor film is formed only on the hydrophilic surface, which reduces a resistive force to migration. Also, reduced size of droplets promotes the thermocapillary motion, which is induced by a gradient in local temperature inside a small microdroplet arising due to the difference in size of adjacent droplets.
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U2 - 10.1021/acs.langmuir.0c00148
DO - 10.1021/acs.langmuir.0c00148
M3 - Article
C2 - 32336101
AN - SCOPUS:85084935669
SN - 0743-7463
VL - 36
SP - 5096
EP - 5105
JO - Langmuir
JF - Langmuir
IS - 19
ER -