TY - JOUR
T1 - Nanoscale-Agglomerate-Mediated Heterogeneous Nucleation
AU - Cha, Hyeongyun
AU - Wu, Alex
AU - Kim, Moon Kyung
AU - Saigusa, Kosuke
AU - Liu, Aihua
AU - Miljkovic, Nenad
N1 - Funding Information:
The authors acknowledge Dr. H. Jeremy Cho of MIT for discussion on absorption theory and the liquid−vapor interface. The authors gratefully acknowledge funding support from the Office of Naval Research (ONR) with Dr. Mark Spector as the program manager (Grant No. N00014-16-1-2625) and the National Science Foundation under Award No. 1554249. N.M. gratefully acknowledges funding support from the International Institute for Carbon Neutral Energy Research (WPI-I2CNER), sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology. Atomic force microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out in part in the Frederick Seitz Materials Research Laboratory Central Facilities, University of Illinois.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/12/13
Y1 - 2017/12/13
N2 - Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH3SH), dimethyl disulfide (CH3SSCH), and dimethyl trisulfide (CH3SSSCH3) on the liquid-vapor interface during water vapor condensation, which act as preferential sites for heterogeneous nucleation after evaporation. The insights gained from this study elucidate fundamental aspects governing the behavior of both short- and long-term heterogeneous nucleation on hydrophobic surfaces, suggest previously unexplored microfabrication and air purification techniques, and present insights into the challenges facing the development of durable dropwise condensing surfaces.
AB - Water vapor condensation on hydrophobic surfaces has received much attention due to its ability to rapidly shed water droplets and enhance heat transfer, anti-icing, water harvesting, energy harvesting, and self-cleaning performance. However, the mechanism of heterogeneous nucleation on hydrophobic surfaces remains poorly understood and is attributed to defects in the hydrophobic coating exposing the high surface energy substrate. Here, we observe the formation of high surface energy nanoscale agglomerates on hydrophobic coatings after condensation/evaporation cycles in ambient conditions. To investigate the deposition dynamics, we studied the nanoscale agglomerates as a function of condensation/evaporation cycles via optical and field emission scanning electron microscopy (FESEM), microgoniometric contact angle measurements, nucleation statistics, and energy dispersive X-ray spectroscopy (EDS). The FESEM and EDS results indicated that the nanoscale agglomerates stem from absorption of sulfuric acid based aerosol particles inside the droplet and adsorption of volatile organic compounds such as methanethiol (CH3SH), dimethyl disulfide (CH3SSCH), and dimethyl trisulfide (CH3SSSCH3) on the liquid-vapor interface during water vapor condensation, which act as preferential sites for heterogeneous nucleation after evaporation. The insights gained from this study elucidate fundamental aspects governing the behavior of both short- and long-term heterogeneous nucleation on hydrophobic surfaces, suggest previously unexplored microfabrication and air purification techniques, and present insights into the challenges facing the development of durable dropwise condensing surfaces.
KW - Heterogeneous nucleation
KW - condensation
KW - durability
KW - hydrophobic
KW - nanoscale agglomerate
KW - volatile organic compounds
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U2 - 10.1021/acs.nanolett.7b03479
DO - 10.1021/acs.nanolett.7b03479
M3 - Article
C2 - 29178810
AN - SCOPUS:85037564381
VL - 17
SP - 7544
EP - 7551
JO - Nano Letters
JF - Nano Letters
SN - 1530-6984
IS - 12
ER -