TY - JOUR
T1 - Evaporation and electrowetting of sessile droplets on slippery liquid-like surfaces and slippery liquid-infused porous surfaces (SLIPS)
AU - Armstrong, Steven
AU - McHale, Glen
AU - Ledesma Aguilar, Rodrigo
AU - Wells, Gary
N1 - Funding Information:
S.A. would like to thank Dr. Andrew M.J. Edwards at Nottingham Trent University for discussions and advice on electrowetting. S.A. would like to acknowledge the University of Northumbria at Newcastle for financial support.
Publisher Copyright:
© 2020 American Chemical Society.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/9/29
Y1 - 2020/9/29
N2 - Sessile droplet evaporation underpins a wide range of applications from inkjet printing to coating. However, drying times can be variable and contact-line pinning often leads to undesirable effects, such as ring stain formation. Here, we show voltage programmable control of contact angles during evaporation on two pinning-free surfaces. We use an electrowetting-on-dielectric approach and Slippery Liquid-Infused Porous (SLIP) and Slippery Omniphobic Covalently Attached Liquid-Like (SOCAL) surfaces to achieve a constant contact angle mode of evaporation. We report evaporation sequences and droplet lifetimes across a broad range of contact angles from 105°−67°. The values of the contact angles during evaporation are consistent with expectations from electrowetting and the Young-Lippman equation. The droplet contact areas reduce linearly in time, and this provides estimates of diffusion coefficients close to the expected literature value. We further find that the total time of eva oration over the broad contact an le ran e studied is onl weakl de endent on the value of the contact angle. We conclude that on these types of slippery surfaces, droplet lifetimes can be predicted and controlled by the droplet’s volume and physical properties (density, diffusion coefficient, and vapor concentration difference to the vapor phase) largely independent of the precise value of contact angle. These results are relevant to applications, such as printing, spraying, coating, and other processes, where controlling droplet evaporation and drying is important.
AB - Sessile droplet evaporation underpins a wide range of applications from inkjet printing to coating. However, drying times can be variable and contact-line pinning often leads to undesirable effects, such as ring stain formation. Here, we show voltage programmable control of contact angles during evaporation on two pinning-free surfaces. We use an electrowetting-on-dielectric approach and Slippery Liquid-Infused Porous (SLIP) and Slippery Omniphobic Covalently Attached Liquid-Like (SOCAL) surfaces to achieve a constant contact angle mode of evaporation. We report evaporation sequences and droplet lifetimes across a broad range of contact angles from 105°−67°. The values of the contact angles during evaporation are consistent with expectations from electrowetting and the Young-Lippman equation. The droplet contact areas reduce linearly in time, and this provides estimates of diffusion coefficients close to the expected literature value. We further find that the total time of eva oration over the broad contact an le ran e studied is onl weakl de endent on the value of the contact angle. We conclude that on these types of slippery surfaces, droplet lifetimes can be predicted and controlled by the droplet’s volume and physical properties (density, diffusion coefficient, and vapor concentration difference to the vapor phase) largely independent of the precise value of contact angle. These results are relevant to applications, such as printing, spraying, coating, and other processes, where controlling droplet evaporation and drying is important.
UR - http://www.scopus.com/inward/record.url?scp=85092120224&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.0c02020
DO - 10.1021/acs.langmuir.0c02020
M3 - Article
C2 - 32882130
AN - SCOPUS:85092120224
SN - 0743-7463
VL - 36
SP - 11332
EP - 11340
JO - Langmuir
JF - Langmuir
IS - 38
ER -