Degradation of Hydrophobic Surface Coatings Under Water Exposure

2018 ◽  
Author(s):  
Matthew A. Trapuzzano ◽  
Rasim Guldiken ◽  
Andrés Tejada-Martínez ◽  
Nathan B. Crane
Keyword(s):  
Contact Angle ◽  
Material Selection ◽  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Water Exposure ◽  
Angle Measurements ◽  
Degradation Rates ◽  
Contact Angle Measurements ◽  
Receding Contact

Many important processes depend on the wetting of liquids on surfaces. Wetting is commonly controlled through material selection, coatings, and/or surface texture, however these means are sensitive to environmental conditions. Some “hydrophobic” fluoropolymer coatings are sensitive to extended water exposure as evidenced by declining contact angles and increasing contact angle hysteresis. Understanding degradation of these coatings is critical to processes that employ them. To accomplish this, contact angle measurements were taken before, during, and after slides coated with FluoroSyl 3750 or Cytop were submerged in water, or vibrated while covered in water. Both methods demonstrated similar changes in advancing contact angle though vibration increased degradation rates significantly. However, it does not simply accelerate the process as different trends are apparent in receding contact angles. The FluoroSyl 3750 showed no clear degradation under either condition. Surface profilometry did not detect any surface morphology differences that might cause contact angle change.

Dynamic Cycling Contact Angle Measurements: Study of Advancing and Receding Contact Angles

2001 ◽  
Vol 243 (1) ◽  
pp. 208-218 ◽  
Author(s):  
C.N.C. Lam ◽  
R.H.Y. Ko ◽  
L.M.Y. Yu ◽  
A. Ng ◽  
D. Li ◽  
...  
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Receding Contact ◽  
Dynamic Cycling

A Simple Apparatus and Technique for Contact-Angle Measurements on Small-Denier Single Fibers

1969 ◽  
Vol 39 (10) ◽  
pp. 958-962 ◽  
Author(s):  
T. H. Grindstaff
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Level Surface ◽  
Simple Apparatus ◽  
Single Fibers ◽  
Angle Measurements ◽  
Surface Method ◽  
Routine Work ◽  
Contact Angle Measurements ◽  
Receding Contact

A simple apparatus and technique are described for measuring contact angles of liquids on small-denier fibers. This technique is based on the level-surface method and can be used to obtain either advancing or receding contact angles. Contact angles determined by this method are accurate and precise and the apparatus is inexpensive, rugged, easy to operate, and suitable for routine work.

The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems

1998 ◽  
Vol 518 ◽  
Author(s):  
Sang-Ho Lee ◽  
Myong-Jong Kwon ◽  
Jin-Goo Park ◽  
Yong-Kweon Kim ◽  
Hyung-Jae Shin
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Fluorocarbon Films ◽  
Perfluorodecanoic Acid ◽  
Large Hysteresis ◽  
Static Contact ◽  
Receding Contact ◽  
Highly Hydrophobic ◽  
Receding Contact Angle

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.

Empirical Formulae in Correlating Droplet Shape and Contact Angle

2016 ◽  
Vol 69 (4) ◽  
pp. 431 ◽  
Author(s):  
Ten It Wong ◽  
Hao Wang ◽  
Fuke Wang ◽  
Sau Leng Sin ◽  
Cheng Gen Quan ◽  
...  
Keyword(s):  
Contact Angle ◽  
Empirical Formula ◽  
Contact Angles ◽  
Shape Deformation ◽  
Direct Identification ◽  
Simple Method ◽  
Droplet Shape ◽  
Spherical Dome ◽  
Angle Measurements ◽  
Contact Angle Measurements

In contact angle measurements, direct identification of the contact angles from images taken from a goniometer suffers from errors caused by optical scatterings. Contact angles can be more accurately identified by the height and width of the droplet. Spherical dome is a simple model used to correlate the contact angles to the droplet shape; however, it features intrinsic errors caused by gravity-induced shape deformation. This paper demonstrates a simple method of obtaining an empirical formula, determined from experiments, to correct the gravity-induced error in the spherical dome model for contact angle calculations. A series of contact angles, heights, and surface contact widths are simultaneously collected for a large amount of samples, and the contact angles are also calculated using the spherical dome model. The experimental data are compared with those obtained from the spherical dome model to acquire an empirical formula for contact angles. Compared with the spherical dome model, the empirical formula can reduce the average errors of the contact angle from –16.3 % to 0.18 %. Furthermore, the same method can be used to correct the gravity errors in the spherical dome for the volume (calculated by height and width), height (calculated by contact angle and volume), and width (calculated by contact angle and volume), and the spherical dome errors can be reduced from –20.9 %, 24.6 %, and –4.8 % to 2 %, –0.13 %, and –0.6 %, respectively. Our method is generic and applicable for all kinds of solvent and substrates, and the derived empirical formulae can be directly used for water droplets on any substrate.

Measurements of the Contact Angles for Various Fluids Which Are Widely Used in the Oilfields to Improve Oil Recovery

2018 ◽  
Author(s):  
M. Elsharafi ◽  
K. Vidal ◽  
R. Thomas
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Rock Face ◽  
Angle Measurements ◽  
Contact Angle Measurements

Contact angle measurements are important to determine surface and interfacial tension between solids and fluids. A ‘water-wet’ condition on the rock face is necessary in order to extract oil. In this research, the objectives are to determine the wettability (water-wet or oil-wet), analyze how different brine concentrations will affect the wettability, and study the effect of the temperature on the dynamic contact angle measurements. This will be carried out by using the Cahn Dynamic Contact Angle. Analyzer DCA 315 to measure the contact angle between different fluids such as surfactant, alkaline, and mineral oil. This instrument is also used to measure the surface properties such as surface tension, contact angle, and interfacial tension of solid and liquid samples by using the Wilhelmy technique. The work used different surfactant and oil mixed with different alkaline concentrations. Varying alkaline concentrations from 20ml to 1ml were used, whilst keeping the surfactant concentration constant at 50ml.. It was observed that contact angle measurements and surface tension increase with increased alkaline concentrations. Therefore, we can deduce that they are directly proportional. We noticed that changing certain values on the software affected our results. It was found that after calculating the density and inputting it into the CAHN software, more accurate readings for the surface tension were obtained. We anticipate that the surfactant and alkaline can change the surface tension of the solid surface. In our research, surfactant is desirable as it maintains a high surface tension even when alkaline percentage is increased.

Contact angles and hysteresis, with some reference to flotation research

1977 ◽  
Vol 30 (1) ◽  
pp. 205 ◽  
Author(s):  
IW Wark
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Gas Phase ◽  
Water Vapour ◽  
Relative Motion ◽  
Solid Surface ◽  
Contact Angles ◽  
Russian School ◽  
Angle Measurements ◽  
Contact Angle Measurements

A technique used in flotation research for contact angle measurements is recommended for wider use. The effect of one aspect of surface roughness on the relative motion of fluid/solid systems is discussed. The function of the water vapour present in the gas phase adjacent to the line of triple contact is examined. A claim of the Russian school of surface chemists is questioned, namely, that a discrete film of water on the solid surface invariably dominates both hysteresis and contact angle.

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