• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.363-363
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• 2010

The high capillarity of a plastic fiber network having superhydrophilic Si-DLC coating is studied. Although the superhydrophilic surface maximize wetting ability on the flat surface, there remains a requirement for the more wettable surface for various applications such as air-filters or liquid-filters. In this research, the PET non-woven fabric surface was realized by superhydrophilic coating. PTE non-woven fabric network was chosen due to its micro-pore structure, cheap price, and productivity. Superhydrophobic fiber network was prepared with a coating of oxgyen plasma treated Si-DLC films using plasma-enhanced chemical vapor deposition (PECVD). We first fabricated superhydrophilic fabric structure by using a polyethylene terephthalate (PET) non-woven fabric (NWF) coated with a nanostructured films of the Si-incorporated diamond-like carbon (Si-DLC) followed by the plasma dry etching with oxygen. The Si-DLC with oxygen plasma etching becomes a superhydrophilic and the Si-DLC coating have several advantages of easy coating procedure at room temperature, strong mechanical performance, and long-lasting property in superhydrophilicity. It was found that the superhydrophobic fiber network shows better wicking ability through micro-pores and enables water to have much faster spreading speed than merely superhydrophilic surface. Here, capillarity on superhydrophilic fabric structure is investigated from the spreading pattern of water flowing on the vertical surface in a gravitational field. As water flows on vertical flat solid surface always fall down in gravitational direction (i.e. gravity dominant flow), while water flows on vertical superhydrophilic fabric surface showed the capillary dominant spreading.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.24.1-24.1
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• 2010

In practical operation, the exposed surfaces may get dirty thus degrade the performance of devices. So the combination of self cleaning and antireflection is very desirable for use in outdoor photovoltaic and displaying devices, self cleaning windows and car windshields. For the purpose of self cleaning, the surface needs to be either superhydrophobic or superhydrophilic. However, in practice AR in the visible region and self cleaning are a pair of competitive properties. To satisfy the requirements for superhydrophobic or superhydrophilic surfaces, high surface roughness is required. But it usually cause severely light scattering. Photo-responsive coatings (TiO2, ZnO etc.) can lead to superhydrophilic. However, the refractive indices are high. Thus for porous structure, controlling pore size in the underwavelength scale to reduce the light scattering is very crucial for highly transparent and self cleaning antireflection coating. Herein, we demonstrate a simple method to make high performance broadband antireflection layer on the glass surface, by "carving" the surface by hot alkali solution. Etched glass has superhydrophilic surface. By chemical modification, it turns to superhydrophobic. Enhanced transparency (up to 97%) in a broad wavelength range was obtained by short time etching. Also antifogging effect has been demonstrated, which may offer advantage for devices working at high humidity environment or underwater. Compositional dependence of the properties was observed by comparing three different commercially available glasses.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.177-181
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• 2001

We have studied superhydrophilic properties of TiO₂thin films in relation with those crystal structures due to the heat treatments. Thin films were fabricated on Si (100) wafers using a conventional Sol-Gel method. Following drying and sintering processes, TiO₂film had an anatase phase with additional heat treatment at 500℃, an rutile phase at 1000℃, and a mixture of anatase and rutile phase at 750℃. All these films got hydrophilic even without any UV illumination. Especially the sample treated at 750℃ had a superhydrophilic contact angle of 5°. We suggested that the superhydrophilic films should have a mixture of anatase and rutile phase for the best performance. The hydrophilic TiO₂films were slowly degraded into the hydrophobic state in the dark room but quickly recovered back with les than 1 hour of UV illumination.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.229-237
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• 2018

Medical silicone tubes are generally used as implants for the treatment of nasolacrimal duct stenosis. However, side effects such as allergic reactions and bacterial infections have been reported following the silicone tube insertion, which cause surgical failure. These drawbacks can be overcome by modifying the silicone tube surface using a functional coating. Here, we report a biocompatible and superhydrophilic surface coating based on a polysaccharide multilayer nanofilm, which can load and release antibacterial and anti-inflammatory agents. The nanofilm is composed of carboxymethylcellulose (CMC) and chitosan (CHI), and fabricated by layer-by-layer (LbL) assembly. The LbL-assembled CMC/CHI multilayer films exhibited superhydrophilic properties, owing to the rough and porous structure obtained by a crosslinking process. The surface coated with the superhydrophilic CMC/CHI multilayer film initially exhibited antibacterial activity by preventing the adhesion of bacteria, followed by further enhanced antibacterial effects upon releasing the loaded antibacterial agent. In addition, inflammatory cytokine assays demonstrated the ability of the coating to deliver anti-inflammatory agents. The versatile nanocoating endows the surface with anti-adhesion and drug-delivery capabilities, with potential applications in the biomedical field. Therefore, we attempted to coat the nanofilm on the surface of an ophthalmic silicone tube to produce a multifunctional tube suitable for patient-specific treatment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.77-83
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• 2022

When carbon dioxide in a liquid becomes supersaturated, carbon dioxide gas bubbles are generated in the liquid, and they ascend to the surface as they develop further. At this time, the inner wall of the cup with carbon gas attached is known as the entrapped gas cavity (EGS); once an EGS is established, it does not disappear and will continuously create carbon bubbles. This bubbling phenomenon can be activated or suppressed by changing the properties of the solid surface in contact with the carbonated liquid. In this study, the foaming of carbonated liquid is promoted or suppressed by modifying the wettability of the surface. A micro/nano surface structure is formed on the surface of an aluminum cup to produce a superhydrophilic surface, and a superhydrophobic surface similar to a lotus leaf is synthesized via fluorination. Experiment results show that the amount of carbon dioxide bubble generated differs significantly in the first few seconds depending on the surface, and that the amount of gas generated after it enters the stabilization period is the same regardless of the wettability of the cup surface.

• Proceedings of the Korea Crystallographic Association Conference
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• 2001.11a
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• pp.25-25
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• 2001

• Polymer Science and Technology
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• v.22 no.3
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• pp.248-255
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• 2011

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.19-24
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• 2012

We demonstrate the desert beetle back mimicking hybrid superhydrophilic/superhydrophobic patterned surface by using the combination method of colloidal lithography and gravure offset printing for nano and micro patterning, respectively. The two methods are cost-effective and industrially available techniques compared to the other nano/micro patterning methods. To verify the water collecting function of the hybrid surface, the water condensation behavior is investigated on the chilled surface in ambient temperature and high humidity. Due to the synergetic effect of drop and film wise condensation, the hybrid superhydrophobic/superhydrophilic surface shows the higher efficiency than one of single wettability surfaces. The work is underway to get the good patterns of hybrid surfaces for water collecting from the dew or fog.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.168-172
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• 2010

Superhydrophilic thin film consisted of positively charged poly (allylamine hydrochloride) (PAH) and negatively charged poly (acrylic acid) (PAA) was fabricated by a layer-by-layer (LBL) self-assembly. Glutaraldehyde (GA) was used in order to increase an adhesion hardness by amine-aldehyde reaction. The surface morphology, thickness, transmittance, water contact angle and adhesion hardness of PAH/PAA thin film with or without GA were measured. The adhesion hardness of PAH/PAA thin film with GA deposition increased over 2 times although the film thickness of PAH/GA/PAA decreased than that of PAH/PAA thin film. The increase of adhesion hardness by amine-aldehyde reaction between PAH and GA was measured by fourier transform infrared (FT-IR) spectroscopy. Fabricated PAH/PAA and PAH/GA/PAA thin films showed water contact angel under $5^{\circ}$ and high transmittance over 91.3% at 550 nm.

• Journal of Adhesion and Interface
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• v.16 no.4
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• pp.152-155
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• 2015

Platinum (Pt) is an easily moldable, anti-corrosive and also good catalyst in a variety of chemical reactions. Platinum can be used in many fields, however, however, the low wettability of platinum substrate in many platinum-based devices has been made a problem when they contact with liquid state environment. In this study, we report a simple and effective self-assembled monolayer coating method which provides tremendously increased wettability on platinum substrate device by using Sodium 3-mercapto-1-propanesulfonic acid solution. After surface modifications, water contact angle of the surfaces displayed less than $10^{\circ}$, representing that surfaces are successfully coated to be super-hydrophilic surface by simple dip coating method.