scholarly journals The wetting properties of frosted glass

2021 ◽  
Vol 13 ◽  
pp. 130006
Author(s):  
Stéphane Dorbolo
Keyword(s):  
Contact Angle ◽  
Optical Properties ◽  
Silicone Oil ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Water Droplets ◽  
Capillary Length ◽  
Wetting Properties ◽  
Travel Distances ◽  
Frosted Glass

Frosted glass is a common, low cost material. Its roughness can be used to control how it is wet by water. In this paper, the wetting properties of silicone oil and water are investigated. For the oil, wetting is total since the oleophilic character of the glass is enhanced by its roughness. Due to the remarkable optical properties of frosted glass, the spreading of oil droplets on its surface was recorded over three months. Frosted glass is a parahydrophilic surface because of its large contact angle hysteresis (up to 80° ). The behaviour of oil and water droplets was compared on a long piece of inclined frosted glass. The trajectories (and the spreading) of the droplets were studied and phenomenological laws were deduced to describe the dependence of the droplet speed on the initial volume of the droplet and the angle of inclination. Such dependences of speed at long travel distances (100 times the capillary length) were deduced and rationalised with a simple model that takes into account the thickness of the wake. Moreover, we analysed the flow inside the wake of water droplets sliding on inclined frosted glass. Suggestions are given on how to exploit drainage of the water droplet wake and the high hysteresis of water within the framework of open microfluidics.

scholarly journals A Simple Method to Create Superhydrophobic Aluminium Surfaces

2012 ◽  
Vol 706-709 ◽  
pp. 2874-2879 ◽  
Author(s):  
R. Jafari ◽  
Masoud Farzaneh
Keyword(s):  
Contact Angle ◽  
Stearic Acid ◽  
Synergistic Effects ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Spray Coating ◽  
Superhydrophobic Surfaces ◽  
Water Contact ◽  
Simple Method ◽  
Static Contact

Superhydrophobic surfaces were prepared using a very simple and low-cost method by spray coating. A high static water contact angle of about 154° was obtained by deposition of stearic acid on an aluminium alloy. However, this coating demonstrated a high contact angle hysteresis (~ 30º). On the other hand, superhydrophobic surfaces with a static contact angle of about 162º and 158º, and a low contact angle hysteresis of about 3º and 5º were respectively obtained by incorporating nanoparticles of SiO2and CaCO3in stearic acid. The excellent resulting hydrophobicity is attributed to the synergistic effects of micro/nanoroughness and low surface energy. A study of the wettability of these surfaces at temperatures ranging from 20 to-10 °C showed that the superhydrophobic surface becomes rather hydrophobic at supercooled temperatures.

scholarly journals Evaporation of Sessile Water Droplets in Presence of Contact Angle Hysteresis

2012 ◽  
Vol 7 (4) ◽  
pp. 82-98 ◽  
Author(s):  
S. Semenov ◽  
V.M. Starov ◽  
R.G. Rubio ◽  
H. Agogo ◽  
M.G. Velarde
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Water Droplets

Controlled defects to link wetting properties to surface heterogeneity

Soft Matter ◽  
2018 ◽  
Vol 14 (42) ◽  
pp. 8643-8650
Author(s):  
Romain Lhermerout ◽  
Kristina Davitt
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Surface Heterogeneity ◽  
Wetting Properties

Contact angle hysteresis and dynamics are measured on surfaces covered with nano-sized defects of known size, shape and density.

Superhydrophobic Surfaces Properties for Anti-Icing

2011 ◽  
Author(s):  
Mohammad Amin Sarshar ◽  
Christopher Swarctz ◽  
Scott Hunter ◽  
John Simpson ◽  
Chang-Hwan Choi
Keyword(s):  
Contact Angle ◽  
Wind Tunnel ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Superhydrophobic Surfaces ◽  
Ice Formation ◽  
Flow Conditions ◽  
Water Droplets ◽  
Dynamic Flow ◽  
Static Contact

In this paper, the iceophobic properties of superhydrophobic surfaces are compared to those of uncoated aluminum and steel plate surfaces as investigated under dynamic flow conditions by using a closed loop low-temperature wind tunnel. Superhydrophobic surfaces were prepared at the Oak Ridge National Laboratory by coating aluminum and steel plates with nano-structured hydrophobic particles. The contact angle and contact angle hysteresis measured for these surfaces ranged from 165–170° and 1–8°, respectively. The superhydrophobic plates along with uncoated control ones were exposed to an air flow of 12 m/s and 20°F with micron-sized water droplets in the icing wind tunnel and the ice formation and accretion were probed by using high speed cameras for 90 seconds. Results show that the developed superhydrophobic coatings significantly delay the ice formation and accretion even with the impingement of accelerated super-cooled water droplets, but there is a time scale for this phenomenon which has a clear relation with contact angle hysteresis of the samples. Among the different superhydrophobic coating samples, the plate having the lowest contact angle hysteresis showed the most pronounced iceophobic effects, while the correlation between static contact angles and the iceophobic effects was not evident. The results suggest that the key parameter for designing iceophobic surfaces is to retain a low contact angle hysteresis, rather than to have only a low contact angle, which can result in more efficient anti-icing properties in dynamic flow conditions.

Micro-, nano- and hierarchical structures for superhydrophobicity, self-cleaning and low adhesion

2009 ◽  
Vol 367 (1894) ◽  
pp. 1631-1672 ◽  
Author(s):  
Bharat Bhushan ◽  
Yong Chae Jung ◽  
Kerstin Koch
Keyword(s):  
Contact Angle ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Hierarchical Structures ◽  
Adhesive Force ◽  
Water Repellent ◽  
Lotus Effect ◽  
Composite State ◽  
Static Contact ◽  
Self Cleaning

Superhydrophobic surfaces exhibit extreme water-repellent properties. These surfaces with high contact angle and low contact angle hysteresis also exhibit a self-cleaning effect and low drag for fluid flow. Certain plant leaves, such as lotus leaves, are known to be superhydrophobic and self-cleaning due to the hierarchical roughness of their leaf surfaces. The self-cleaning phenomenon is widely known as the ‘lotus effect’. Superhydrophobic and self-cleaning surfaces can be produced by using roughness combined with hydrophobic coatings. In this paper, the effect of micro- and nanopatterned polymers on hydrophobicity is reviewed. Silicon surfaces patterned with pillars and deposited with a hydrophobic coating were studied to demonstrate how the effects of pitch value, droplet size and impact velocity influence the transition from a composite state to a wetted state. In order to fabricate hierarchical structures, a low-cost and flexible technique that involves replication of microstructures and self-assembly of hydrophobic waxes is described. The influence of micro-, nano- and hierarchical structures on superhydrophobicity is discussed by the investigation of static contact angle, contact angle hysteresis, droplet evaporation and propensity for air pocket formation. In addition, their influence on adhesive force as well as efficiency of self-cleaning is discussed.

scholarly journals Towards optimization of patterned superhydrophobic surfaces

2007 ◽  
Vol 4 (15) ◽  
pp. 643-648 ◽  
Author(s):  
Bharat Bhushan ◽  
Michael Nosonovsky ◽  
Yong Chae Jung
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Hydrophobic Surface ◽  
Dimensional Parameter ◽  
Wetting Properties ◽  
Spacing Factor ◽  
Composite Interface ◽  
Experimental Values ◽  
Solid Liquid Interface ◽  
Solid Liquid

Experimental and theoretical study of wetting properties of patterned Si surfaces with cylindrical flat-top pillars of various sizes and pitch distances is presented. The values of the contact angle (CA), contact angle hysteresis (CAH) and tilt angle (TA) are measured and compared with the theoretical values. Transition from the composite solid–liquid–air to the homogeneous solid–liquid interface is investigated. It is found that the wetting behaviour of a patterned hydrophobic surface depends upon a simple non-dimensional parameter, the spacing factor, equal to the pillar diameter divided by the pitch. The spacing factor controls the CA, CAH and TA in the composite interface regime, as well as destabilization and transition to the homogeneous interface. We show that the assumption that the CAH is a consequence of the adhesion hysteresis and surface roughness leads to the theoretical values of the CAH that are in a reasonably good agreement with the experimental values. By decreasing the spacing factor, the values of CA=170°, CAH=5° and TA=3° are achieved. However, with further decreasing of the spacing factor, the composite interface destabilizes.

Superhydrophobic and Highly Oleophilic Polystyrene Fibers (PS) with Delayed Freezing Time and Effective Oil Adsorption

2018 ◽  
Vol 941 ◽  
pp. 2232-2236
Author(s):  
Reza Jafari ◽  
Marc Chameau ◽  
Masoud Farzaneh ◽  
Gelareh Momen
Keyword(s):  
Contact Angle ◽  
Superhydrophobic Surface ◽  
Contact Angle Hysteresis ◽  
Aluminum Surface ◽  
Motor Oil ◽  
Freezing Time ◽  
Water Droplets ◽  
Flexible Behavior ◽  
Oil Adsorption ◽  
Very High

We present an efficient and simple approach for preparing superhydrophobic-superoleophilic polystyrene (PS) fibers via electrospinning. Bead-on-string fibers from a 5% PS solution and micro-sized fibers from a 20% PS solution were combined to achieve a surface having very high contact angle (about 160°) and low contact angle hysteresis. The presence of bead-on-string fibers increases the superhydrophobicity of the sorbent. The micro-sized PS fibers improve the mechanical properties of the electrospun mat through their elastic and flexible behavior. An evaluation of wettability at a low temperature (-10 oC) showed a delayed freezing time for water droplets on the superhydrophobic surface. Water droplets on a polished aluminum surface froze more quickly (about 6 seconds) than droplets on the fabricated superhydrophobic surface (about 500 seconds). Finally, the oil adsorption capacity of the developed superhydrophobic PS fibers, which have a porous surface structure, showed values of 69.1, 69.3 and 61.2 g/g for canola oil, olive oil and motor oil, respectively.

scholarly journals Influence of Abrasive Load on Wettability and Corrosion Inhibition of a Commercial Superhydrophobic Coating

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 887
Author(s):  
Arjun Manoj ◽  
Rahul Ramachandran ◽  
Pradeep L. Menezes
Keyword(s):  
Contact Angle ◽  
Corrosion Inhibition ◽  
Mechanical Stability ◽  
Electrochemical Impedance ◽  
Contact Angle Hysteresis ◽  
Open Circuit ◽  
Superhydrophobic Coating ◽  
Corrosion Properties ◽  
Wetting Properties ◽  
Before And After

The poor mechanical stability of hydrophobic and superhydrophobic surfaces and coatings severely hinder their commercial and industrial applicability. In addition to being expensive and time-consuming to manufacture, the ability of these coatings to maintain their non-wetting properties after mechanical abrasion and wear is currently not well-understood. In this work, the influence of increasing abrasive loads on the roughness, wettability, and corrosion inhibition properties of a commercial superhydrophobic coating was studied. It was shown that the wetting and corrosion properties of the superhydrophobic coating was affected by the abrasive load. Increasing abrasive loads were applied using a tribometer and the electrochemical response was studied using open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. The wetting and roughness behavior of the coating before and after the application of the abrasive load was characterized using contact angle, contact angle hysteresis, and optical profilometry. The protective properties of the superhydrophobic coating was observed to deteriorate as the abrasive load increased. Similarly, after a specific abrasive load, the coating transitioned from the Cassie-Baxter state of wetting into that of the Wenzel state.

scholarly journals Wetting Properties of Polyetheretherketone Plasma Activated and Biocoated Surfaces

2019 ◽  
Vol 3 (1) ◽  
pp. 40 ◽  
Author(s):  
Kacper Przykaza ◽  
Klaudia Woźniak ◽  
Małgorzata Jurak ◽  
Agnieszka Wiącek
Keyword(s):  
Contact Angle ◽  
Free Energy ◽  
Surface Free Energy ◽  
Contact Angle Hysteresis ◽  
Biologically Active ◽  
Adhesive Properties ◽  
Surface Sterilization ◽  
Wetting Properties ◽  
Angle Measuring ◽  
Modified Surface

Polyetheretherketone (PEEK) biomaterial is a polymer which has been widely used since the early 90s as a material for human bone implant preparations. Nowadays it is increasingly used due to its high biocompatibility and easily modeling, as well as better mechanical properties and price compared to counterparts made of titanium or platinum alloys. In this paper, air low-temperature and pressure plasma was used to enhance PEEK adhesive properties as well as surface sterilization. On the activated polymeric carrier, biologically-active substances have been deposited with the Langmuir-Blodgett technique. Thereafter, the surface was characterized using optical profilometry, and wettability was examined by contact angle measuring. Next, the contact angle hysteresis (CAH) model was used to calculate the surface free energy of the modified surface of PEEK. The variations of wettability and surface free energy were observed depending on the deposited monolayer type and its components.

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