TY - JOUR
T1 - Droplet pinning on spherical surfaces
T2 - Prediction of apparent advancing and receding angles
AU - Lin, Chang Sheng
AU - Zhu, Zhang Lei
AU - Yin, Wan Zhong
AU - Jiang, You Hua
N1 - Publisher Copyright:
© 2021, Chongqing Wujiu Periodicals Press. All rights reserved.
PY - 2021
Y1 - 2021
N2 - This paper aims to predict apparent advancing and receding angles, i.e., the angles between the liquid-gas interface and the horizontal plane, of droplets on spherical surfaces using the intrinsic advancing and receding contact angles, namely the angle between the liquid-gas interface and the solid-liquid interface. Based on the Gibbs free energy, droplet volume, and the correlation between the contact angle and the apparent angle, this study predicted the apparent angles of droplets on spherical surfaces and the predicted values were verified by experimental results. Results show that intrinsic advancing and receding contact angles are (91±2)° and (55±3)°, respectively, on a flat PET (Polyethylene Terephthalate) surface. For droplets on the edge of advancing or receding, the contact angles equal to the corresponding intrinsic contact angles when the Gibbs free energy of the system is at the minimal value, where the corresponding apparent angles are apparent advancing and receding angles. Therefore, the apparent advancing and receding angles of droplets on spherical surfaces can be predicted by minimizing the system Gibbs free energy. It is shown that the measured apparent advancing angles are (118±3)°, (110±2)°, (103±2)°, and (100±2)°, the apparent receding angles are (82±2)°, (71±2)°, (64±3)°, and (62±2)°, on spherical surfaces with radius of curvatures of 2 mm, 4 mm, 6 mm, and 8 mm, respectively. Such measured results agree well with the prediction. In conclusion, this paper develops a model that predicts apparent advancing and receding angles of droplets on spherical surfaces using the intrinsic advancing and receding contact angles, droplet volume, and radius of curvatures of the spherical surfaces.
AB - This paper aims to predict apparent advancing and receding angles, i.e., the angles between the liquid-gas interface and the horizontal plane, of droplets on spherical surfaces using the intrinsic advancing and receding contact angles, namely the angle between the liquid-gas interface and the solid-liquid interface. Based on the Gibbs free energy, droplet volume, and the correlation between the contact angle and the apparent angle, this study predicted the apparent angles of droplets on spherical surfaces and the predicted values were verified by experimental results. Results show that intrinsic advancing and receding contact angles are (91±2)° and (55±3)°, respectively, on a flat PET (Polyethylene Terephthalate) surface. For droplets on the edge of advancing or receding, the contact angles equal to the corresponding intrinsic contact angles when the Gibbs free energy of the system is at the minimal value, where the corresponding apparent angles are apparent advancing and receding angles. Therefore, the apparent advancing and receding angles of droplets on spherical surfaces can be predicted by minimizing the system Gibbs free energy. It is shown that the measured apparent advancing angles are (118±3)°, (110±2)°, (103±2)°, and (100±2)°, the apparent receding angles are (82±2)°, (71±2)°, (64±3)°, and (62±2)°, on spherical surfaces with radius of curvatures of 2 mm, 4 mm, 6 mm, and 8 mm, respectively. Such measured results agree well with the prediction. In conclusion, this paper develops a model that predicts apparent advancing and receding angles of droplets on spherical surfaces using the intrinsic advancing and receding contact angles, droplet volume, and radius of curvatures of the spherical surfaces.
KW - Apparent angle
KW - Contact angle
KW - Gibbs free energy
KW - Pinning
KW - Spherical surface
UR - http://www.scopus.com/inward/record.url?scp=85114502911&partnerID=8YFLogxK
U2 - 10.16490/j.cnki.issn.1001-3660.2021.08.009
DO - 10.16490/j.cnki.issn.1001-3660.2021.08.009
M3 - 文章
AN - SCOPUS:85114502911
SN - 1001-3660
VL - 50
SP - 95
EP - 100
JO - Surface Technology
JF - Surface Technology
IS - 8
M1 - 1001-3660(2021)08-0095-06
ER -