Tailoring Surface Hydrophobicity of Commercial Polyimide by Laser-Induced Nanocarbon Texturing

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Moataz Abdulhafez ◽  
Angela J. McComb ◽  
Mostafa Bedewy
Keyword(s):  
Contact Angle ◽  
Surface Characterization ◽  
Surface Engineering ◽  
Processing Parameters ◽  
Surface Hydrophobicity ◽  
Spot Size ◽  
Contact Angles ◽  
Water Contact ◽  
Wide Range ◽  
Surface Nanostructure

Abstract The growth of laser-induced nanocarbons, referred to here as laser-induced nanocarbon (LINC) for short, directly on polymeric surfaces is a promising route toward surface engineering of commercial polymers. This paper aims to demonstrate how this new approach can enable achieving varied surface properties based on tuning the nanostructured morphology of the formed graphitic material on commercial polyimide (Kapton) films. We elucidate the effects of tuning laser processing parameters on the achieved nanoscale morphology and the resulting surface hydrophobicity or hydrophilicity. Our results show that by varying lasing power, rastering speed, laser spot size, and line-to-line gap sizes, a wide range of water contact angles are possible, i.e., from below 20 deg to above 110 deg. Combining water contact angle measurements from an optical tensiometer with LINC surface characterization using optical microscopy, electron microscopy, and Raman spectroscopy enables building the process–structur–property relationship. Our findings reveal that both the value of contact angle and the anisotropic wetting behavior of LINC on polyimide are dependent on their hierarchical surface nanostructure which ranges from isotropic nanoporous morphology to fibrous morphology. Results also show that increasing gap sizes lead to an increase in contact angles and thus an increase in the hydrophobicity of the surface. Hence, our work highlight the potential of this approach for manufacturing flexible devices with tailored surfaces.

Laser-Induced Nanocarbon Formation for Tuning Surface Properties of Commercial Polymers

2020 ◽  
Author(s):  
Moataz Abdulhafez ◽  
Angela J. McComb ◽  
Mostafa Bedewy
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Surface Characterization ◽  
Surface Engineering ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Structure Property ◽  
Water Contact ◽  
Wide Range ◽  
Commercial Polymers

Abstract The growth of laser-induced nanocarbons, referred to here are LINC for short, directly on polymeric surfaces is a promising route toward surface engineering of commercial polymers. This paper aims to demonstrate how this new approach can enable achieving varied surface properties based on tuning the nanostructured morphology of the formed graphitic material on commercial polyimide (Kapton) films. We elucidate the effects of tuning laser processing parameters on the achieved nanoscale morphology and the resulting surface hydrophobicity or hydrophilicity. Our results show that by varying lasing power, rastering speed, laser spot size, and line-to-line gap sizes, a wide range of water contact angles are possible, i.e. from below 20° to above 110°. Combining water contact angle measurements from an optical tensiometer with LINC surface characterization using optical microscopy, electron microscopy, and Raman spectroscopy enables building the process-structure-property relationship. Our findings reveal that both the value of contact angle and the anisotropic wetting behavior of LINC on polyimide are dependent on their hierarchical surface nanostructure which ranges for isotropic nanoporous morphology to fibrous morphology. Results also show that increasing gap sizes lead to an increase in contact angles and thus an increase in the hydrophobicity of the surface. Hence, our work highlight the potential of this approach for manufacturing flexible devices with tailored surfaces.

The Wetting of Insect Cuticles by Water

1955 ◽  
Vol 32 (3) ◽  
pp. 591-617 ◽  
Author(s):  
M. W. HOLDGATE
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Surface Composition ◽  
Contact Angles ◽  
Aquatic Species ◽  
Water Contact ◽  
Calliphora Erythrocephala ◽  
Wetting Properties ◽  
Wide Range

1. The water contact angles of insects show a wide range of variation, which is broadly correlated with surface roughness and with habitat. 2. The contact angles of species inhabiting stored products or carrion are greatly modified by contamination. This produces large variations between apparently similar individuals. 3. In terrestrial insects surface roughness increases the contact angles to very large apparent values. Detailed analyses of its effect have been made in the pupa of Tenebrio molitor and the adult Calliphora erythrocephala. In some aquatic insects surface roughness leads to a reduction in the contact angles; this has been studied in the nymph of Anax imperator. 4. Prolonged immersion in water causes a lowering of the contact angles of all the insects examined, and the low angles of many aquatic species may therefore be the direct effect of their environment. In some aquatic species there is evidence of the active maintenance of a large contact angle during life. 5. Changes in contact angle accompany processes of cuticle secretion and will occur at any moult if changes in roughness or habitat take place. 6. The observed variations of surface properties can be explained without assuming any variation in the chemical composition of the cuticle surface. Wetting properties are of little value as indicators of cuticle surface composition. 7. The biological aspects of insect surface properties are briefly discussed.

scholarly journals Assessment of Super-Hydrophobic Textured Coatings on AA6082 Aluminum Alloy

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 352 ◽  
Author(s):  
Luigi Calabrese ◽  
Amani Khaskhoussi ◽  
Salvatore Patane ◽  
Edoardo Proverbio
Keyword(s):  
Contact Angle ◽  
Surface Morphology ◽  
In Situ Polymerization ◽  
Contact Angles ◽  
Measuring System ◽  
Hydrophobic Surfaces ◽  
Short Term Treatment ◽  
Water Contact ◽  
Water Separation ◽  
Wide Range

Superhydrophobicity is one of the most required surface properties for a wide range of application such as self-cleaning, anti-corrosion, oil-water separation, anti-icing, and anti-bioadhesion. Recently, several methods have been developed to produce nature inspired super-hydrophobic surfaces. Nevertheless, these methods require a complicated process and expensive equipment. In order to overcome these issues, we propose three different methods to obtain nature-inspired super-hydrophobic surfaces: short-term treatment with boiling water, HF/HCl and HNO3/HCl concentrated solution etching. Afterwards, a thin layer of octadecylsilane was applied by in situ polymerization on all pre-treated surfaces. Eventually, all substrates were dried for 3 h at 100 °C to complete the silane curing. Scanning electron microscopy (SEM), contact angle measuring system and atomic force microscope (AFM) were used to characterize the surfaces. Surface morphology analysis showed that each method results in a specific dual hierarchical nano-/micro-structure. The corresponding water contact angles ranged from 160° to nearly 180°. The best results were observed for HF etched Al 6082 surface were water contact angle above 175° was achieved. Furthermore, a scheme able to assess the relationship between hydrophobic behavior and surface morphology was finally proposed.

scholarly journals The Effect of Hydroxyl on the Superhydrophobicity of Dodecyl Methacrylate (LMA) Coated Fabrics through Simple Dipping-Plasma Crosslinked Method

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1263
Author(s):  
Liyun Xu ◽  
Yu Zhang ◽  
Ying Guo ◽  
Ruiyun Zhang ◽  
Jianjun Shi ◽  
...  
Keyword(s):  
Thermoplastic Polyurethane ◽  
Hydrophobic Effect ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Binding Property ◽  
Interesting Phenomenon ◽  
Water Contact ◽  
Capacitively Coupled ◽  
Pet Fabric ◽  
Dodecyl Methacrylate

In order to obtain stable superhydrophobicity, suitable hydrophobic treatment agents should be selected according to different material properties. In this paper, cotton and poly(ethylene terephthalate) (PET) fabrics were respectively coated with dodecyl methacrylate (LMA) via argon combined capacitively coupled plasma (CCP), and the surface hydrophobicity and durability of the treated cotton and polyester fabrics are also discussed. An interesting phenomenon happened, whereby the LMA-coated cotton fabric (Cotton-g-LMA) had better water repelling and mechanical durability properties than LMA-coated PET fabric (PET-g-LMA), and LMA-coated hydroxyl-grafted PET fabrics (PET fabrics were successively coated with polyethylene glycol (PEG) and LMA, PET-g-PEG & LMA) had a similar performance to cotton fabrics. The water contact angles of Cotton-g-LMA, PET-g-LMA and PET-g-PEG & LMA were 156°, 153° and 155°, respectively, and after 45 washing cycles or 1000 rubbing cycles, the corresponding water contact angles decreased to 145°, 88°, 134° and 146°, 127° and 143°, respectively. Additionally, thermoplastic polyurethane (TPU) and polyamides-6 (PA6) fabrics all exhibited the same properties as the PET fabric. Therefore, the grafting of hydroxyl can improve the hydrophobic effect of LMA coating and the binding property between LMA and fabrics effectively, without changing the wearing comfort.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

scholarly journals Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

2018 ◽  
Vol 2 (4) ◽  
pp. 74 ◽  
Author(s):  
Abinash Tripathy ◽  
Patryk Wąsik ◽  
Syama Sreedharan ◽  
Dipankar Nandi ◽  
Oier Bikondoa ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Surface Density ◽  
Room Temperature ◽  
High Surface ◽  
Secondary Growth ◽  
Water Contact ◽  
Growth Step ◽  
Si Substrates ◽  
Wide Range

Functional ZnO nanostructured surfaces are important in a wide range of applications. Here we report the simple fabrication of ZnO surface structures at near room temperature with morphology resembling that of sea urchins, with densely packed, μm-long, tapered nanoneedles radiating from the urchin center. The ZnO urchin structures were successfully formed on several different substrates with high surface density and coverage, including silicon (Si), glass, polydimethylsiloxane (PDMS), and copper (Cu) sheets, as well as Si seeded with ZnO nanocrystals. Time-resolved SEM revealed growth kinetics of the ZnO nanostructures on Si, capturing the emergence of “infant” urchins at the early growth stage and subsequent progressive increases in the urchin nanoneedle length and density, whilst the spiky nanoneedle morphology was retained throughout the growth. ε-Zn(OH)2 orthorhombic crystals were also observed alongside the urchins. The crystal structures of the nanostructures at different growth times were confirmed by synchrotron X-ray diffraction measurements. On seeded Si substrates, a two-stage growth mechanism was identified, with a primary growth step of vertically aligned ZnO nanoneedle arrays preceding the secondary growth of the urchins atop the nanoneedle array. The antibacterial, anti-reflective, and wetting functionality of the ZnO urchins—with spiky nanoneedles and at high surface density—on Si substrates was demonstrated. First, bacteria colonization was found to be suppressed on the surface after 24 h incubation in gram-negative Escherichia coli (E. coli) culture, in contrast to control substrates (bare Si and Si sputtered with a 20 nm ZnO thin film). Secondly, the ZnO urchin surface, exhibiting superhydrophilic property with a water contact angle ~ 0°, could be rendered superhydrophobic with a simple silanization step, characterized by an apparent water contact angle θ of 159° ± 1.4° and contact angle hysteresis ∆θ < 7°. The dynamic superhydrophobicity of the surface was demonstrated by the bouncing-off of a falling 10 μL water droplet, with a contact time of 15.3 milliseconds (ms), captured using a high-speed camera. Thirdly, it was shown that the presence of dense spiky ZnO nanoneedles and urchins on the seeded Si substrate exhibited a reflectance R < 1% over the wavelength range λ = 200–800 nm. The ZnO urchins with a unique morphology fabricated via a simple route at room temperature, and readily implementable on different substrates, may be further exploited for multifunctional surfaces and product formulations.

Preparation of Super Hydrophobic Surfaces by the Stainless Steel Wire Mesh as Templates

2012 ◽  
Vol 562-564 ◽  
pp. 56-59 ◽  
Author(s):  
Jian Zhuang ◽  
Meng Meng Du ◽  
Heng Zhi Cai ◽  
Ya Jun Zhang ◽  
Da Ming Wu
Keyword(s):  
Contact Angle ◽  
Stainless Steel ◽  
Steel Wire ◽  
Contact Angles ◽  
Wire Mesh ◽  
Stainless Steel Wire ◽  
Hydrophobic Surfaces ◽  
Water Contact ◽  
Stainless Steel Wire Mesh ◽  
Steel Wire Mesh

A facile method for manufacturing super hydrophobic surfaces is presented using the stainless steel wire mesh as templates. The rough surfaces of polymers including polycarbonate, polypropylene and PMMA are prepared with hot embossing on different specifications of stainless steel wire mesh. Scanning electron microscopy (SEM) results reveal that the surfaces roughness of the polymers can be controlled by selecting templates. Contact angle measurement shows that the water contact angles(WCA) rise with the increase of surface roughness, especially, the water contact angle on the PC surfaces prepared with specifications of 635mesh screen can reach to 152.3°, alias super hydrophobic surfaces.

scholarly journals AACVD Synthesis and Characterization of Iron and Copper Oxides Modified ZnO Structured Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 471 ◽  
Author(s):  
Martha Claros ◽  
Milena Setka ◽  
Yecid P. Jimenez ◽  
Stella Vallejos
Keyword(s):  
Contact Angle ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Contact Angles ◽  
Copper Oxides ◽  
Water Contact ◽  
X Ray ◽  
Hydrophobic Behavior

Non-modified (ZnO) and modified (Fe2O3@ZnO and CuO@ZnO) structured films are deposited via aerosol assisted chemical vapor deposition. The surface modification of ZnO with iron or copper oxides is achieved in a second aerosol assisted chemical vapor deposition step and the characterization of morphology, structure, and surface of these new structured films is discussed. X-ray photoelectron spectrometry and X-ray diffraction corroborate the formation of ZnO, Fe2O3, and CuO and the electron microscopy images show the morphological and crystalline characteristics of these structured films. Static water contact angle measurements for these structured films indicate hydrophobic behavior with the modified structures showing higher contact angles compared to the non-modified films. Overall, results show that the modification of ZnO with iron or copper oxides enhances the hydrophobic behavior of the surface, increasing the contact angle of the water drops at the non-modified ZnO structures from 122° to 135° and 145° for Fe2O3@ZnO and CuO@ZnO, respectively. This is attributed to the different surface properties of the films including the morphology and chemical composition.

scholarly journals A spherical particle straddling a fluid/gas interface in an axisymmetric straining flow

1990 ◽  
Vol 217 ◽  
pp. 263-298 ◽  
Author(s):  
J. A. Stoos ◽  
L. G. Leal
Keyword(s):  
Contact Angle ◽  
Spherical Particle ◽  
Numerical Solutions ◽  
Contact Angles ◽  
Boundary Integral ◽  
Equilibrium Contact Angle ◽  
Equilibrium Configurations ◽  
Wide Range ◽  
The Stability ◽  
Neutrally Buoyant

Numerical solutions, obtained via the boundary-integral technique, are used to consider the effect of a linear axisymmetric straining flow on the existence of steady-state configurations in which a neutrally buoyant spherical particle straddles a gas–liquid interface. The problem is directly applicable to predictions of the stability of particle capture in flotation processes, and is also of interest in the context of contact angle and surface tension measurements. A primary goal of the present study is a determination of the critical capillary number, Cac, beyond which an initially captured particle is pulled from the interface by the flow, and the dependence of Cac on the equilibrium contact angle θc. We also present equilibrium configurations for a wide range of contact angles and subcritical capillary numbers.

scholarly journals Amphiphobic Nanostructured Coatings for Industrial Applications

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 787 ◽  
Author(s):  
Federico Veronesi ◽  
Giulio Boveri ◽  
Mariarosa Raimondo
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Friction Reduction ◽  
Hybrid Coatings ◽  
Wetting Behavior ◽  
Wide Range ◽  
Solid Liquid

The search for surfaces with non-wetting behavior towards water and low-surface tension liquids affects a wide range of industries. Surface wetting is regulated by morphological and chemical features interacting with liquid phases under different ambient conditions. Most of the approaches to the fabrication of liquid-repellent surfaces are inspired by living organisms and require the fabrication of hierarchically organized structures, coupled with low surface energy chemical composition. This paper deals with the design of amphiphobic metals (AM) and alloys by deposition of nano-oxides suspensions in alcoholic or aqueous media, coupled with perfluorinated compounds and optional infused lubricant liquids resulting in, respectively, solid–liquid–air and solid–liquid–liquid working interfaces. Nanostructured organic/inorganic hybrid coatings with contact angles against water above 170°, contact angle with n-hexadecane (surface tension γ = 27 mN/m at 20 °C) in the 140–150° range and contact angle hysteresis lower than 5° have been produced. A full characterization of surface chemistry has been undertaken by X-ray photoelectron spectroscopy (XPS) analyses, while field-emission scanning electron microscope (FE-SEM) observations allowed the estimation of coatings thicknesses (300–400 nm) and their morphological features. The durability of fabricated amphiphobic surfaces was also assessed with a wide range of tests that showed their remarkable resistance to chemically aggressive environments, mechanical stresses and ultraviolet (UV) radiation. Moreover, this work analyzes the behavior of amphiphobic surfaces in terms of anti-soiling, snow-repellent and friction-reduction properties—all originated from their non-wetting behavior. The achieved results make AM materials viable solutions to be applied in different sectors answering several and pressing technical needs.

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