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.

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.

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.

Diamond-Like Carbon Films for Silicon Passivation in Microelectromechanical Devices

1995 ◽  
Vol 383 ◽  
Author(s):  
M. R. Houston ◽  
R. T. Howe ◽  
K Komvopoulos ◽  
R. Maboudian
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Microelectromechanical Systems ◽  
Adhesion Force ◽  
Contact Angles ◽  
Vacuum Arc ◽  
Diamond Like Carbon ◽  
Adhesion Forces ◽  
Water Contact

ABSTRACTThe surface properties of diamond-like carbon (DLC) films deposited by a vacuum arc technique on smooth silicon wafers are presented with specific emphasis given to stiction reduction in microelectromechanical systems (MEMS). The low deposition temperatures afforded by the vacuum arc technique should allow for easy integration of the DLC films into the current fabrication process of typical surface micromachines by means of a standard lift-off processing technique. Using X-ray photoelectron spectroscopy (XPS), contact angle analysis, and atomic force microscopy (AFM), the surface chemistry, microroughness, hydrophobicity, and adhesion forces of DLC-coated Si(100) surfaces were measured and correlated to the measured water contact angles. DLC films were found to be extremely smooth and possess a water contact angle of 87°, which roughly corresponds to a surface energy of 22 mJ/m2. It is shown that the pull-off forces measured by AFM correlate well with the predicted capillary forces. Pull-off forces are reduced on DLC surfaces by about a factor of five compared to 10 nN pull-off forces measured on the RCA-cleaned silicon surfaces. In the absence of meniscus forces, the overall adhesion force is expected to decrease by over an order of magnitude to the van der Waals attractive force present between two DLC-coated surfaces- To further improve the surface properties of DLC, films were exposed to a fluorine plasma which increased the contact angle to 99° and lowered the pull-off force by approximately 20% over that obtained with as-deposited DLC. The significance of these results is discussed with respect to stiction reduction in micromachines.

scholarly journals Modification of Surface Hydrophobicity of PLA/PE and ABS/PE Polymer Blends by ICP Etching and CFx Coating

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5578
Author(s):  
Vedrana Lovinčić Milovanović ◽  
Cédric Guyon ◽  
Ivana Grčić ◽  
Michael Tatoulian ◽  
Domagoj Vrsaljko
Keyword(s):  
Contact Angle ◽  
3D Printing ◽  
Surface Morphology ◽  
Polymer Blends ◽  
Surface Properties ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Etching Time ◽  
Fused Filament Fabrication ◽  
Icp Etching

The flow regime inside the channel of 3D printed microreactors is defined by the surface properties of the channel walls. Polylactide (PLA) and acrylonitrile/butadiene/styrene (ABS) are two polymers that are the most common in additive manufacturing using fused filament fabrication, commonly known as “3D printing”. With the aim of developing new materials for the 3D printing of microreactors whose channel surface hydrophobicity could be modified, PLA and ABS were blended with cheaper and widely used polymers-high-density polyethylene (PE-HD) and low-density polyethylene (PE-LD). Polymer blend surfaces were treated with inductively coupled plasma (ICP) and coated by fluorocarbon-based material (CFx) plasma deposition treatment in order to modify surface hydrophobicity. It has been shown that the modification of surface morphology of PLA polymer blends can be achieved by ICP etching and CFx coating, while this was not possible for ABS polymer blends under the conducted treatment conditions. The treated surface of PLA/PE-HD 90/10 showed a contact angle of 121.6° which is 36° higher than the contact angle measured on the untreated surface. Surfaces that have achieved contact angles higher than 120° have an “island like” surface morphology. Samples with higher “islands” showed higher contact angles, that confirmed that the hydrophobicity also depends on the height of the “islands”. Furthermore, it has been found that etching time significantly impacts the contact angle values and surface morphology of the PLA polymer blends, while the CFx coating time does not have significant impact on the surface properties.

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 Tunable Crystalline Phases in UV-Curable PEG-Grafted Ladder-Structured Silsesquioxane/Polyimide Composites

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2295 ◽  
Author(s):  
Ryung Il Kim ◽  
Ju Ho Shin ◽  
Jong Suk Lee ◽  
Jung-Hyun Lee ◽  
Albert S. Lee ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Surface Properties ◽  
Weight Ratio ◽  
Hybrid Polymer ◽  
Water Contact ◽  
Uv Curable ◽  
Wide Range ◽  
Drastic Increase ◽  
Polyimide Composites ◽  
Crystalline Polyethylene

A series of UV-curable hybrid composite blends containing a carboxylic acid functionalized polyimidewith varying amounts of high molecular weight (~1 K) PEG-grafted ladder-structured polysilsesquioxanes copolymerized with methacryl groups were fabricated and their structural, thermal, mechanical, and surface properties characterized. At a composite weight ratio of polyimide above 50 wt.%, a stark shift from amorphous to crystalline polyethylene glycol (PEG) phases were observed, accompanied by a drastic increase in both surface moduli and brittleness index. Moreover, fabricated composites were shown to have a wide range water contact angle, 9.8°–73.8°, attesting to the tunable surface properties of these amphiphilic hybrid polymer composites. The enhanced mechanical properties, combined with the utility of tunable surface hydrophilicity allows for the possible use of these hybrid polymer composites to be utilized as photosensitive polyimide negative photoresists for a myriad of semiconductor patterning processes.

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.

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