Statistical Contact Angle Analyses with the High-Precision Drop Shape Analysis (HPDSA) Approach: Basic Principles and Applications

Heib, Florian; Schmitt, Michael

doi:10.3390/coatings6040057

Cited by 83 publications

(78 citation statements)

References 79 publications

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“…Polar groups and unpolished and clean metallic surfaces cause high surface energy. In contrast, aliphatic carbon chains have less surface energy and higher contact angles . Therefore, according to this contact angle data, the untreated PU film synthesized from castor oil is the most hydrophobic film.…”

Section: Resultsmentioning

confidence: 78%

Low‐pressure plasma surface modification of polyurethane films with chitosan and collagen biomolecules

Bahrami

Khorasani

Mahdavi

et al. 2019

J of Applied Polymer Sci

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Polyurethane (PU) was synthesized using castor oil and a trade grade of hexamethylene diisocyanate, and then PU films were prepared for wound dressing applications. The PU films were then plasma treated with the low-pressure nitrogen plasma to functionalize with peroxide and hydroperoxide groups in order to attach with acrylic acid monomers. Therefore, the polyacrylic acid polymer branches were formed on the film surfaces. Carboxylic acid groups were activated by N-(3-dimethylaminopropyl)-N 0 -ethyl carbodiimide hydrochloride/N-hydroxysuccinimide and bonded with chitosan and collagen biomolecules. Untreated, nitrogen plasma treated, polyacrylic acid grafted, and finally chitosan and collagen-immobilized PU films were characterized by several tests. The tests included the attenuated total reflectance Fourier transform infrared spectroscopy, static contact angle, atomic force microscopy, scanning electron microscopy, fibroblast L929 cell culture, and antibacterial activity assay to evaluate their in vitro cytocompatibility. The results confirmed that chitosan and collagen were immobilized successfully on the PU surfaces. The chitosan-immobilized PU and collagen-immobilized PU improved the adhesion and proliferation of fibroblast cells compared to untreated PU films. The chitosanmodified PU films exhibit the best antibacterial properties.

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Section: Resultsmentioning

confidence: 78%

Low‐pressure plasma surface modification of polyurethane films with chitosan and collagen biomolecules

Bahrami

Khorasani

Mahdavi

et al. 2019

J of Applied Polymer Sci

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“…The HIREC coating has demonstrated its superhydrophobic characteristic [24][25][26][27]. A water contact angle characterized the hydrophobicity of the surface under static conditions [28,29]. Figure 2 is an example of the shape of a water droplet on the coating surface.…”

Section: Figure 1 Shows a Schematic Of The Experimental Setup An Opementioning

confidence: 99%

“…The water contact angle, θ C , of the HIREC coating was 150 degrees. The contact angle of water repellent material is formulated as shown in Equations (1) and (2) [28,29]. Equation 1describes the Wenzel model, which relates the contact angle, θ C , to the contact angle of a smooth surface, θ S .…”

Section: Figure 1 Shows a Schematic Of The Experimental Setup An Opementioning

confidence: 99%

“…f 1 and f 2 are the coefficients of the surface areas of the gas interaction and water interaction. On the other hand, a contact angle hysteresis is a common parameter used to characterize the hydrophobicity of the surface under dynamic conditions [28,29]. The contact angle hysteresis is the difference between advancing and receding angles.…”

Section: Figure 1 Shows a Schematic Of The Experimental Setup An Opementioning

confidence: 99%

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Pinned Droplet Size on a Superhydrophobic Surface in Shear Flow

2020

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The recent development of a superhydrophobic surface enhances the droplet shedding under a shear flow. The present study gives insights into the effects of shear flow on a pinned droplet over a superhydrophobic surface. To experimentally simulate the change in the size of a sessile droplet on an aerodynamic surface, the volume of the pinned droplet is expanded by water supplied through a pore. Under a continuous airflow that provides a shear flow over the superhydrophobic surface, the size of a pinned water droplet shed from the surface is experimentally characterized. The air velocity ranges from 8 to 61 m/s, and the size of pinned droplets shed at a given air velocity is measured using an instantaneous snapshot captured with a high-speed camera. It is found that the size of the shedding pinned droplet decreases as air velocity increases. At higher air velocities, shedding pinned droplets are fully immersed in the boundary layer. The present findings give a correlation between critical air velocity and the size of pinned droplets shed from the pore over the superhydrophobic surface.

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“…Characterizations of the resulting samples were realized utilizing scanning electron microscope (SEM, JEOL 6460), atomic force microscope (AFM), optical microscope, and goniometer (Kyowa, model -DM 501). A care was taken obtaining the high resolution and stable images for the contact angle measurements 25 . Coated samples were gold plated prior to obtain SEM micrographs of surfaces.…”

Section: Experimental and Characterization Toolsmentioning

confidence: 99%

Heating Enhancement of a Droplet on a Superhydrophobic Surface

Al‐Sharafi

Yilbaş

Al‐Qahtani

2020

Sci Rep

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Enhancement of heating of a droplet on a hydrophobic surface is investigated. A vertical metal (column) pin is introduced in the droplet and the fluid heating, due to the column pin, is examined. The droplet heating is initiated at the hydrophobic surface and the column pin located in the droplet. The effect of the flow currents on the thermal fields inside the droplet fluid is assessed. An experiment is conducted to assure the velocity simulation results while using the particle image velocimetry (PIV). We demonstrated that the velocity simulations are in good agreement with the data obtained from PIV measurements. Two circulating structures are observed inside the droplet, which are related to the buoyancy and the Marangoni currents. The presence of the column pin changes the number of circulations cells to four inside the droplet. Heated fluid in region of the droplet-solid interface is transferred by the buoyancy current towards the droplet sides and heat diffusion increases temperature rise in the droplet central region. The Nusselt number attains larger values for the droplet with column pin configuration than that of the free droplet, which becomes apparent for the large droplet volumes. The Bond number improves with the presence of the column pin in the droplet; but, the Bond number values become smaller than unity for all the droplets with and without column pin configurations considered. Heating of a water droplet on a hydrophobic plate results in the Marangoni and the buoyancy currents, which generate circulating structures in the droplet. The Bond and the Nusselt numbers are affected by the various parameters, some of which include droplet volume, droplet contact angle, temperature ranges, droplet fluid, and etc. The development of the Marangoni current is associated with the surface tension gradient (γ d dT

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Statistical Contact Angle Analyses with the High-Precision Drop Shape Analysis (HPDSA) Approach: Basic Principles and Applications

Cited by 83 publications

References 79 publications

Low‐pressure plasma surface modification of polyurethane films with chitosan and collagen biomolecules

Low‐pressure plasma surface modification of polyurethane films with chitosan and collagen biomolecules

Pinned Droplet Size on a Superhydrophobic Surface in Shear Flow

Heating Enhancement of a Droplet on a Superhydrophobic Surface

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