• KSBB Journal
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• v.23 no.1
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• pp.70-76
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• 2008

Surface of hydrophobic media was modified to become hydrophilic by ion beam irradiation. Fixed bed biofilm reactors packed with or without surface modification were used to remove organics, nitrogen, and phosphorus from sewage. This system composed of anoxic/oxic cycles to increase the nutrient removal. A cylindrical polyethylene was used as a packing media in this study. With 12 hours of hydraulic retention time (HRT), the reactors with and without surface modification showed 95% and 92% $COD_{cr}$ removal, respectively. Both reactors showed over 95% $COD_{cr}$ removals for a longer HRT of 16 hours. Nitrogen removal ranged 54.8% to 70.2% for the surface modified system and 57.5% to 76.5% for the non-modified system under same condition. Finally, phosphorus removal ranged 59.4% to 69.8% for the surface modified system and 51.3% to 63.4% for the non-modified system under same condition. From this study organics and phosphorus were better removed in using surface modified media and vice versa for nitrogen removal.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.46-52
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• 2006

High-density micromass culture was needed to take three dimensions culture with ASCs(adipose derived stromal cells) and chondrogenesis. However, the synthetic polymer has hydrophobic character and low affinity to cells and other biomolecules. Therefore, the surface modification without changes of physical and chemical properties is necessary for more suitable condition to cells and biomolecules. This study was performed to investigate the effect of surface modification of poly (lactic-co-glycolic acid)(PLGA) scaffold by plasma treatment (P(+)) on the adhesion, proliferation and chondrogenesis of ASCs, and not plasma treatment (P(-)). ASCs were isolated from human subcutaneous adipose tissue obtained by lipectomy and liposuction. At 1 hour 30 minutes and 3days after cell seeding onto the P(-) group and the P(+) group, total DNA amount of attached and proliferated ASCs markedly increased in the P(+) group (p < 0.05). The changes of the actin under confocal microscope were done for evaluation of cellular affinity, at 1 hour 30 minutes, the shape of the cells was spherical form in all group. At 3rd day, the shape of the cells was fiber network form and finely arranged in P(+) group rather than in P(-) group. RT-PCR analysis of cartilage-specific type II collagen and link protein were expressed in 1, 2 weeks of induction. Amount of Glycoaminoglycan (GAG) markedly increased in P(+) group(p < 0.05). In a week, extracellular matrix was not observed in the Alcian blue and Safranin O staining. However in 2 weeks, it was observed that sulfated proteoglycan increased in P(+) group rather than in P(-) group. In conclusion, we recognized that plasma treatment of PLGA scaffold could increase the hydrophilic property of cells, and provide suitable environment for high-density micromass culture to chondrogenesis

• Polymer(Korea)
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• v.35 no.2
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• pp.157-160
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• 2011

In this paper, poly (dimethyl siloxane) (PDMS) was modified using electron beam irradiation and its property was investigated. PDMS sheets prepared using a conventional thermal curing method were irradiated by electron beams at absorbed doses between 20 and 200 kGy and their properties were characterized using swelling degree and contact angle measurements, universal testing machine (UTM), thermogravimetric analyzer (TGA), and X -ray photoelectron spectrometer (XPS). The results of the swelling degree measurements, UTM, and TGA revealed that the swelling degree of the irradiated PDMS sheets was reduced down to 24% in comparison to the control sheet, and their compression strength and thermal decomposition temperature increased up to maximum 2.5 MFa and $10^{\circ}C$, respectively, due to the increase in crosslinking density by irradiation. In addition, on the basis of the results of contact angle measurements and XPS, the wettability of the PDMS sheets was enhanced up to 24% owing to the generation of hydrophilic functional groups on the PDMS surface by oxidation during electron beam irradiation.

• Polymer(Korea)
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• v.36 no.2
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• pp.177-181
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• 2012

This study presents the preparation of double emulsions in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. To improve the wettability of hydrophilic continuous phase onto a hydrophobic PDMS microchannel, the surface was modified with 3-(trimethoxysilyl) propyl methacrylate (TPM) and then sequentially reacted with acrylic acid monomer solution, which produced selective covalent bonding between acrylic acids and methacrylate groups. For the proof of selective surface modification, tolonium chloride solution was used to identify the modified region and we confirmed that the approach was successfully performed. When water containing 0.5% w/w sodium dodecyl sulfate and 1% w/w Span80 with hexadecane were loaded into the selectively modified microfluidic channels, we can produce stable double emulsion. Based on the spreading coefficients, we predict the morphology of double emulsions. Our proposed method efficiently produces monodisperse double emulsions having 48.5 ${\mu}m$(CV:1.6%) core and 65.1 ${\mu}m$ (CV:1.6%) shell. Furthermore, the multiple emulsions having different numbers of core were easily prepared by simple control of flow rates.

• Clean Technology
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• v.27 no.2
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• pp.124-131
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• 2021

As declarations of carbon neutrality are spreading throughout the world, much research is being conducted on biodegradable polymers. In this study, nanocellulose, which comprises the largest amount of natural polymer currently available in the world, was proposed as a substitute for non-biodegradable polymers. We chose to modify the surface functional group of crystalline nanocellulose using glycidoxypropyl trimethoxysilane (GPTMS), which is a silane coupling agent, and the product was then used to form a film with low density polyethylene (LDPE). We then conducted measurements using a Fourier transform infrared spectrophotometer (FT-IR) in addition to measuring hydrophilic/lipophilicity of the surface functional group modification of crystalline nitrocellulose as well as that of a polymer composite using the hybrid nanocellulose (H-NC). For compatibility with petroleum-based polymers, the best tensile strength and transparency was found when the H-NC was reacted at pH 14 and 1 wt% compared with LDPE. From the test results, we found that it is possible to modify the surface functional groups of nanocellulose using a silane coupling agent. In addition, the high compatibility of nanocellulose with petroleum-based polymers is expected to help in reaching carbon neutrality by reducing the use of fossil fuels.

• Elastomers and Composites
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• v.35 no.1
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• pp.19-28
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• 2000

The fundamental study of additional silicone impression material has been performed by comparing the other import products. In order to estimate the possibility of usage of the impression material developed in this study, the several techniques such as IR, EDX, DSC, TGA, rubber rheometer, and contact angle measurement were used. According to the results, there were not any product satisfying all properties required in the impression material. The impression material developed in this study showed best mechanical properties among the all impression materials. However. the wetting property should be studied more by an introduction of a hydrophilic surfactant or modification of a base polymer.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.11-17
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• 2010

Modifying surface of activated carbon for the electrode of EDLC with an organic electrolyte was investigated to improve the electrochemical performance of EDLC by the microwave radiation. Three kinds of activated carbons, prepared activated carbon from petroleum cokes and pitch cokes and commercial activated carbon BP-25, were used for this study. For all investigated activated carbons, hydrophilic functional groups-containing oxygen disappeared from the surface of activated carbon as microwave radiation. And as microwave radiation time was increased, the specific surface area and total pore volume of activated carbons were reduced and average pore diameter were increased. From theses effects, interfacial resistance of EDLC with the modified activated carbon electrode was drastically decreased, and discharge capacitance was increased although the specific surface area of activated carbon was reduced by this microwave radiation.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.98-103
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• 2010

The effect of plasma treatment on surface characteristics of polycarbonate (PC) films was investigated using low pressure plasma and atmospheric pressure plasma with oxygen and argon. Untreated PC has a contact angle of $82.31^{\circ}$ with de-ionized water which reduced to $9.17^{\circ}$ as the lowest value after being treated with a low pressure plasma treatment with oxygen. Increase of delivered powers such as RF and AC with a high frequency and gas flow rates was not effective to reduce contact angles dramatically but gave the trend of reducing gradually. The surface of PC treated with plasma shows a low contact angle but the contact angle increases rapidly according to the exposure time in air ambient. Oxygen plasma was more effective to generate the polar functional group regardless of the type of plasma. Conclusively, a low plasma treatment with oxygen is more recommendable when the hydrophilic surface of PC is required.

• Journal of Korean Dental Science
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• v.11 no.1
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• pp.5-13
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• 2018

Purpose: Surface treatment with pH buffering agent has been developed to achieve higher and faster osseointegration. The aim of this study was to evaluate its influence by measuring removal torque and analyzing histological characteristics. Materials and Methods: Titanium implants with following surfaces were used in this study: sand-blasted acid-etched (SA) surface (SA group as control I group), SA surface in calcium chloride aqueous solution (CA group as control II group) and SA surface coated with pH buffering agent (pH group as test group). Removal torque test after 2 weeks and bone-to-implant contact and bone area analyses at 2 and 4 weeks were performed. Result: The rotational torque values at 2 weeks were significantly higher in pH group ($107.5{\pm}6.2Ncm$, P<0.05). The mean values of bone-to-implant contact at 2 and 4 weeks were both higher in pH group ($93.0%{\pm}6.4%$ at 2 weeks, $88.6%{\pm}5.5%$ at 4 weeks) than in SA group ($49.7%{\pm}9.7%$ at 2 weeks, $47.3%{\pm}20.1%$ at 4 weeks) and CA group ($73.7%{\pm}12.4%$ at 2 weeks, $72.5%{\pm}10.9%$ at 4 weeks) with significances (P<0.05). The means of bone area showed significantly higher numbers in pH group ($39.5%{\pm}11.3%$ at 2 weeks, $71.9%{\pm}10.9%$ at 4 weeks, P<0.05). Conclusion: Our findings demonstrated that surface modification with pH buffering agent improved early osseointegration with superior biomechanical property.

• KSBB Journal
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• v.16 no.5
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• pp.505-510
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• 2001

The preparation, characterization and drug release behaviour of drug(indomethacin) loaded Poly(L-lactic acid)(PLA), tarmarind acetate and levan acetate mircospheres were investigated. Hydrophobic tarmarind acetate and levan acetate were prepared by chemical modification of hydrophilic tarmaried gum and levan and microspheres were made by a solvent evaporation method. In the case of poly(L-lactic acid) microspheres, drug release rate was effected by polymer-drug ratios and drum release was sustained by increasing of polymer content. The yield of microspheres were effected by many factors and the mean size was below 1 $\mu$m, The IND release profiles from tarmarind acetate and levan acetate micropheres were more slightly less than ploy(L-lactic acid) microspheres.