Sessile drop technique

About: Sessile drop technique is a research topic. Over the lifetime, 2827 publications have been published within this topic receiving 68943 citations.

Effect of corrugations of the three-phase line on the drop size dependence of contact angles

Abstract: Conflicting observations of the drop size dependence of contact angles have been reported in literature: while some investigators reported an increase of contact angle with an increase in drop size, others reported a decrease. The former was discussed in terms of negative line tension, and the latter was considered as an effect of positive line tension. While some investigators accept the possibility of positive as well as negative line tension, the present authors suspect that line tension, at least for solid—liquid—fluid systems, is positive. In the present paper, by developing a model to calculate the mean contact angle of a sessile drop with a corrugated three-phase line, we show that the observed increase of contact angles with the increase in drop size does not necessarily imply a negative line tension; it may well be a consequence of the corrugations of the three-phase line caused by heterogeneity of the solid surface.

Axisymmetric Drop Shape Analysis (ADSA) and its Applications

Abstract: Publisher Summary This chapter discusses axisymmetric drop shape analysis (ADSA) and its application. It provides an account of these ADSA methodologies. It contains a description of the numerical algorithms and their implementation. The applicability of ADSA is illustrated extensively for the investigation of surface tension measurements with pendant and sessile drops and contact angle experiments with sessile drops using both axisymmetric drop shape analysis - profile (ADSA-P) and axisymmetric drop shape analysis - diameter (ADSA-D). The advantages of pendant and sessile drop methods are numerous. In comparison with a method such as the Wilhelmy plate technique, only small amounts of the liquid are required. Drop shape methods easily facilitate the study of both liquid-vapor and liquid-liquid interfacial tensions. Also, the methods have been applied to materials ranging from organic liquids to molten metals and from pure solvents to concentrated solutions. There is no limitation to the magnitude of surface or interracial tension that can be measured: The methodology presented in this chapter works as well at 103 mJ/m 2 as at 10 -3 mJ/m 2.

Effect of evaporation on the contact angle of a sessile drop on solid substrates

Abstract: The effect of evaporation on the contact angle of a sessile drop of water on glass and polycarbonate substrates has been investigated. It has been observed that the contact radius depends on the initial mass of the drop and remains constant throughout the progress of evaporation. The evaporation rates in both systems are proportional to the contact radii of sessile drops. The contact angle, however, decreases as evaporation proceeds. In the case of water-glass system, the contact angle decreases almost linearly with time. On the other hand, in water-polycarbonate system, the contact angle shows a considerable departure from linearity. It has been shown that the non-linear behavior of contact angle becomes more pronounced with increasing initial contact angle.