• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.35-39
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• 2015

Polyvinylchloride (PVC) thin films having a microporous structure could be prepared by using the solubility difference in solvents. PVC thin film with a water contact angle of $150^{\circ}$ or more was obtained from the PVC solution consisting of the mixture of tetrahydrofuran as a solvent and propanol as a non-solvent. In the drying process of dip-coated PVC film, the increase of drying temperature reduced the tendency of roughened surface, which led the decrease of surface hydrophobicity. As the addition of propanol in the solution with 1 wt% PVC increased, the uniformity of surface roughness was improved. In the case of oxygen plasma treatments, even though the surface structure of PVC thin film was not notably changed, the surface property of the film was changed from the super-hydrophobicity to hydrophilicity as a function of the plasma exposing time.

• Membrane Journal
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• v.16 no.2
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• pp.106-114
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• 2006

This study is concerned with preparation of chlorine resistant (CR) thin layer composite (TFC) membranes. The novel method for making CR membranes from commercially available RO membranes is based on sol-gel condensation of trialkoxyalkylsilane derivatives. The silane coupling agents used in this study have different number of alkyl carbon chain group (methyltriethoxysilane; METES and octyltriethoxysilane; OCTES). The OCTES composite membranes have a significant tolerance to chlorine compared to commercial polyamide RO membrane or METES composite membranes. The surface properties of membranes were examined to explain a significant difference of chlorine tolerance between OCTES composite membrane and the other two membranes. In this study, we tried several surface analyses to explain difference of chlorine tolerance. The element composition results of surface analysis by EDX confirmed that both silane fixed on polyamide firmly, The surface roughness and contact angle results showed long chain alkyl group of OCTES enhancing hydrophobicity considerably than METES. The hydrophobicity plays an important role in chlorine resistance of membrane.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.227-232
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• 1990

S. marcescens cultured at $30^{\circ}C$ with vigorous shaking was shown to produce red-pigment, prodigiosin, in the senescent phase of growth. Also, it showed many hydrophobic characteristrics, which were tested by the adherence to noncharged surfaces of polystyrene dishes, a typical agent for the binding of hydrophobic cells and molecules. However, when the cell was cultured at $37^{\circ}C$, it no longer produced either red pigment or hydrophobic materials. Therefore, the bacteria cultured at $37^{\circ}C$ was completely washed-out from the polystyrene dishes at the copious washing step with tap water, in contrast to the cell cultured at $30^{\circ}C$ which was sticked onto the polystyrene dishes very tightly. The lipid compositions extracted from the S. marcescens cultured at $30^{\circ}C$ or $37^{\circ}C$ were very different from each other; the phospholipids, glycolipids and unidentified lipids were produced from the cell cultured at $30^{\circ}C$, whereas large amounts of serratamolide, amphipathic compound, were produced from the cell cultured at $37^{\circ}C$. The data suggest that the pronounced cell surface hydrophobicity of the S. marcescens is mediated by a combination of several surface factors that were affected by cultivation time and temperatures.

• Korean journal of food and cookery science
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• v.9 no.1
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.

• Restorative Dentistry and Endodontics
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• v.43 no.1
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• pp.1.1-1.8
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• 2018

Objectives: To determine the effect of root canal irrigants on the hydrophobicity and adherence of Staphylococcus epidermidis (S. epidermidis) to root canal dentin in vitro. Materials and Methods: Root dentin blocks (n = 60) were randomly divided into 4 groups based on the irrigation regimen: group 1, saline; group 2, 5.25% sodium hypochlorite (NaOCl); group 3, 5.25% NaOCl followed by 17% ethylenediaminetetraacetic acid (EDTA); group 4, same as group 3 followed by 2% chlorhexidine (CHX). The hydrophobicity of S. epidermidis to root dentin was calculated by cell surface hydrophobicity while the adherence was observed by fluorescence microscopy, and bacteria were quantified using ImageJ software (National Institutes of Health). Statistical analysis of the data was done using Kruskal-Wallis test and Mann-Whitney U test (p = 0.05). Results: The hydrophobicity and adherence of S. epidermidis to dentin were significantly increased after irrigating with group 3 (NaOCl-EDTA) (p < 0.05), whereas in group 4 (NaOCl-EDTA-CHX) both hydrophobicity and adherence were significantly reduced (p < 0.05). Conclusions: The adherence of S. epidermidis to dentin was influenced differently by root canal irrigants. Final irrigation with CHX reduces the bacterial adherence and may impact biofilm formation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.1-6
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• 2004

In this study, heat and discharge treatments are arbitrary simulated for finding out the initiations and processes of surface degradation on the surface of polymer for using as a PCB substrate. Thermal-treatment changed the surface to the hydrophobic one with the increase of contact angle and surface potential decay, respectively. The XPS spectrum showed that the increased hydrophobicity in thermal treatment was originated from the continuous decrease of side-chains caused by secessions of oxygen groups and the increase of unsaturated double bond in carbon chains. Also, thermal-treatment caused the discoloration on the point of treated surface. These phenomena were attributed to the generation of ether group. In the chemical change by discharge treatment, a lot of side-chains occurred on the treated surface, and so the hydrophilicity increased as time elapsed.

• Textile Coloration and Finishing
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• v.33 no.3
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• pp.113-119
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• 2021

Polypropylene fiber has the advantages of light weight, heat retention and antibacterial properties, but it is difficult to expand its market because it cannot be dyed or imparted functionality due to its hydrophobic properties. Atmospheric pressure plasma processing can modify the surface of the fiber and create polar functional groups on the surface of the fiber. In this study, an experiment was conducted on the hydrophilization of the ultra-hydrophobicity of polypropylene through plasma processing and surface changes before and after plasma processing. The ultra-hydrophobicity of polypropylene is the cause of impossible for dyeing and imparting functionality. Untreated polypropylene became hydrophilic, and it was confirmed that the ratio of oxygen and carbon(O/C) increased about 11 times from untreated polypropylene 0.017 to plasma-treated polypropylene 0.190.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1068-1078
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• 2004

In this paper we investigated the characteristics of surface degradation in silicone rubber due to corona exposure and recovery mechanism. It was shown that surface free energy was 22.42 mJ/$m^2$ on initial sample but surface free energy was approximately increased to 71.14 mJ/$m^2$ after 45 minutes. However, surface free energy on silicone rubber after corona discharge treatment was completely recovered within a short time due to diffusion of low molecular weight(LMW) silicone fluid. It was shown that corona discharge insured the increase of diffusible LMW chains, which could lead to recover the surface hydrophobicity. 200～370 g/mol distribution of LMW silicone fluid which was extracted by solvent-extraction with gel permeation chromatography (GPC) was contributed to recovery. The surface degradation characteristics on silicone rubbers and the recovery mechanism based on our results were discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.598-606
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• 2000

In this paper we investigated the relation between the surface degradations and anti-pollution characteristics of Room Temperature Vulcanized(RTV) silicone rubber coating that has different roughness through immersing into saline water. We utilized several analytic techniques such as atomic force microscopy(AFM) scaning electron microscopy(SEM) contact angle Salt Deposit Density(SDD) and average leakage current under the condition of salt fog. It is found that the surface roughness of treated RTV silicone rubber increased and the hydrophobicity of sample surface decreased with increasing the duration o immersion into water due to the erosion of base polymer the melting down alumina trihydrate(ATH) and the diffusion of Low Molecular weight(LMW) fluid. Despite the roughness of surface had been increased by water immersion excellant anti-pollution and recovery characteristics were maintained and SDD saturated to 0.1~0.14mg/cm$^2$. The average leakage current under salt fog increased with surface roughness. Measurement of average leakage current will be helpful to investigate surface degradation and lifetime expectation of RTV silicone coating.

• Polymer(Korea)
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• v.28 no.1
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• pp.3-9
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• 2004

Silane modified perfluoropolyethers (SPFPE) was synthesized as a self-assembled mono-layers (SAMs) thin film for micro-electro mechanical system (MEMS). SPFPE was compared to the Perfluoropolyethers (PFPE) as well as octadecyltrichlorosilane (OTS) and perfluorooctyltrichlorosilane (FOTS) with respect to the development of hydrophobicity in the SAMs surface. SPFPE shows less hydrophobicity than those of OTS and FOTS. Thermal annealing of SPFPE SAMs resulted in the enhancement of hydrophobicity as much as those of OTS and FOTS. The SAMs formed from SPFPE were found to be similar as OTS and FOTS SAMs with smooth R$\sub$a/ values of 0.3 nm. However, the flexible chain mobility of SPFPE resulted in 50% reduction as much as the fiction force in OTS.