scholarly journals Evaporation of Sessile Droplets of Polyelectrolyte/Surfactant Mixtures on Silicon Wafers

2021 ◽  
Vol 5 (1) ◽  
pp. 12 ◽  
Author(s):  
Andrew Akanno ◽  
Lionel Perrin ◽  
Eduardo Guzmán ◽  
Sara Llamas ◽  
Victor M. Starov ◽  
...  
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Contact Length ◽  
Silicon Wafers ◽  
Surfactant Mixtures ◽  
Diallyldimethylammonium Chloride ◽  
Advancing Contact Angle ◽  
Universal Law ◽  
Wetting Behaviors ◽  
Evaporation Stage

The wetting and evaporation behavior of droplets of aqueous solutions of mixtures of poly(diallyldimethylammonium chloride) solution, PDADMAC, with two different anionic surfactants, sodium laureth sulfate, SLES, and sodium N-lauroyl N-methyl taurate, SLMT, were studied in terms of the changes of the contact angle θ and contact length L of sessile droplets of the mixtures on silicon wafers at a temperature of 25 °C and different relative humidities in the range of 30–90%. The advancing contact angle θa was found to depend on the surfactant concentration, independent of the relative humidity, with the mixtures containing SLES presenting improved wetting behaviors. Furthermore, a constant droplet contact angle was not observed during evaporation due to pinning of the droplet at the coffee-ring that was formed. The kinetics for the first evaporation stage of the mixture were independent of the relative humidity, with the evaporation behavior being well described in terms of the universal law for evaporation.

scholarly journals A new temperature- and humidity-dependent surface site density approach for deposition ice nucleation

2015 ◽  
Vol 15 (7) ◽  
pp. 3703-3717 ◽  
Author(s):  
I. Steinke ◽  
C. Hoose ◽  
O. Möhler ◽  
P. Connolly ◽  
T. Leisner
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Active Surface ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Aerosol Size Distribution ◽  
Surface Site ◽  
Linear Behavior ◽  
Temperature And Humidity

Abstract. Deposition nucleation experiments with Arizona Test Dust (ATD) as a surrogate for mineral dusts were conducted at the AIDA cloud chamber at temperatures between 220 and 250 K. The influence of the aerosol size distribution and the cooling rate on the ice nucleation efficiencies was investigated. Ice nucleation active surface site (INAS) densities were calculated to quantify the ice nucleation efficiency as a function of temperature, humidity and the aerosol surface area concentration. Additionally, a contact angle parameterization according to classical nucleation theory was fitted to the experimental data in order to relate the ice nucleation efficiencies to contact angle distributions. From this study it can be concluded that the INAS density formulation is a very useful tool to describe the temperature- and humidity-dependent ice nucleation efficiency of ATD particles. Deposition nucleation on ATD particles can be described by a temperature- and relative-humidity-dependent INAS density function ns(T, Sice) with ns(xtherm) = 1.88 ×105 · exp(0.2659 · xtherm) [m−2] , (1) where the temperature- and saturation-dependent function xtherm is defined as xtherm = −(T−273.2)+(Sice−1) ×100, (2) with the saturation ratio with respect to ice Sice >1 and within a temperature range between 226 and 250 K. For lower temperatures, xtherm deviates from a linear behavior with temperature and relative humidity over ice. Also, two different approaches for describing the time dependence of deposition nucleation initiated by ATD particles are proposed. Box model estimates suggest that the time-dependent contribution is only relevant for small cooling rates and low number fractions of ice-active particles.

Urine Advancing Contact Angle on Several Surfaces

2009 ◽  
Vol 23 (15) ◽  
pp. 1917-1923 ◽  
Author(s):  
Evan A. Thomas ◽  
Darwin H. Poritz ◽  
Dean L. Muirhead
Keyword(s):  
Contact Angle ◽  
Advancing Contact Angle

Spontaneous Spreading of a Droplet: The Role of Solid Continuity and Advancing Contact Angle

Langmuir ◽  
2018 ◽  
Vol 34 (17) ◽  
pp. 4945-4951 ◽  
Author(s):  
Youhua Jiang ◽  
Yujin Sun ◽  
Jaroslaw W. Drelich ◽  
Chang-Hwan Choi
Keyword(s):  
Contact Angle ◽  
Advancing Contact Angle

Special Wetting Behaviors on Canna Leaf and its Dependence with Microstructures

2013 ◽  
Vol 779-780 ◽  
pp. 64-67
Author(s):  
Xiao Hua Yang ◽  
Jian Hua Xiao ◽  
Jun Fei Ou
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Lotus Leaf ◽  
Micro Scale ◽  
High Adhesion ◽  
Rose Petal ◽  
High Contact Angle ◽  
Wetting Behaviors ◽  
The Rose ◽  
Rose Petal Effect

Like lotus leaf and rose petal, the canna leaf also has excellent super hydrophobicity.The purpose of this paper is to systematically study the super hydrophilicity of canna leaf. Using SEM to observe the morphology of the canna leaf, and analytical balance to measure the adhensive force between water droplet and the leaf . This paper shows that the first type of the canna leaf which has co-exsitence of the nanocrumb and micro-scale convex cells has the high contact angle and low contact angle hysteresis similar to lotus leaf. The another type on the leaf has high contact angle but high adhesion in a certain extent like the rose petal effect, whose microstructure unitarily simple has the micro convex cells, do not distributed anything of nanoscale.

scholarly journals Leaf surface structures enable the endemic Namib desert grass Stipagrostis sabulicola to irrigate itself with fog water

2012 ◽  
Vol 9 (73) ◽  
pp. 1965-1974 ◽  
Author(s):  
A. Roth-Nebelsick ◽  
M. Ebner ◽  
T. Miranda ◽  
V. Gottschalk ◽  
D. Voigt ◽  
...  
Keyword(s):  
Contact Angle ◽  
Leaf Surface ◽  
Contact Angle Hysteresis ◽  
Maximum Size ◽  
Large Degree ◽  
Namib Desert ◽  
Fog Water ◽  
Water Conduction ◽  
Key Factor ◽  
Advancing Contact Angle

The Namib grass Stipagrostis sabulicola relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed. Stipagrostis sabulicola has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of S. sabulicola contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment.

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