• Title, Summary, Keyword: hydrophilic polymer

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Synthesis of Porous $TiO_2$ Thin Films Using PVC-g-PSSA Graft Copolymer and Their Use in Dye-sensitized Solar Cells (PVC-g-PSSA 가지형 공중합체를 이용한 다공성 $TiO_2$ 박막의 합성 및 염료감응 태양전지 응용)

  • Byun, Su-Jin;Seo, Jin-Ah;Chi, Won-Seok;Shul, Yong-Gun;Kim, Jong-Hak
    • Membrane Journal
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    • v.21 no.2
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    • pp.193-200
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    • 2011
  • An amphiphilic graft copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). Mesoporous titanium dioxide $(TiO_2)$ films with crystalline anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA graft copolymer. Titanium isopropoxide (TTIP), a $TiO_2$ precursor was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grew to form mesoporous $TiO_2$ films, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amounts of P25 nanoparticies. The energy conversion efficiency reached up to 2.7% at 100 mW/$cm^2$ upon using quasi-solid-state polymer electrolyte.

Surface Modification of Proton Exchange Membrane by Introduction of Excessive Amount of Nanosized Silica (과량 실리카 도입을 통한 고분자 전해질막 표면 개질)

  • Park, Chi Hoon;Kim, Ho Sang;Lee, Young Moo
    • Membrane Journal
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    • v.24 no.4
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    • pp.301-310
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    • 2014
  • In this study, the silica nanoparticles were considerably chosen to improve a dimensional stability, proton transport and electrochemical performance of the resulting inorganic-organic nanocomposite membranes. For this purpose, hydrophobic silica (Aerosil$^{(R)}$ 812, Degussa) and hydrophilic silica (Aerosil$^{(R)}$ 380, Degussa) nanoparticles were, respectively, introduced into a Sulfonated poly(arylene ether sulfone) (SPAES) polymer matrix. The $SiO_2$ particles are evenly dispersed in a SPAES matrix by the aid of a non-ionic surfactant (Pluronics$^{(R)}$ L64). A $SiO_2$ content plays an important role in membrane microstructures and membrane properties such as proton conductivity and water uptake. Therefore, to study nanocomposite membranes with excessive amount of silica, the content of silica nanoparticles were increased up to 5 wt%. Interestingly, a hydrophobic $SiO_2$ containing nanocomposite membrane showed better electrochemical performance (29% higher than pristine SPAES) despite of low proton conductivity due to its adhesive properties with a catalyst layer in a single cell test. All the silica-SPAES membranes exhibited better performance than a pristine SPAES membrane.

Fabrication of Carbon Microneedle Arrays with High Aspect Ratios and The Control of Hydrophobicity of These Arrays for Bio-Applications (고종횡비 탄소 마이크로니들 어레이의 제조 및 생체응용을 위한 소수성 표면의 제어)

  • Lee, Jung-A;Lee, Seok-Woo;Lee, Seung-Seob;Park, Se-Il;Lee, Kwang-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1721-1725
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    • 2010
  • This paper reports the fabrication of geometry-controlled carbon microneedles by a backside exposure method and pyrolysis. The SU-8 microneedles are a polymer precursor in a carbonization process, which geometries such as base diameter, spacing, and aspect ratio can be controlled in a photolithography step. Using this fabrication method, highly reproducible carbon microneedles, which have high aspect ratios of more than 10 and very sharp nanotips, can be realized. The quartz surface with carbon microneedles becomes very hydrophilic and its wettability is adjusted by carrying out the silane treatment. In the carbon microneedle array ($3\;{\mu}m{\times}3\;{\mu}m$), the contact angle is extremly enhanced (${\sim}180^{\circ}$); this will be advantageous in developing low-drag microfluidics and labs-on-a-chip as well as in other bio-applications.

Investigation on Reaction Products From Oxidative Coupling Reactions of 1-Naphthol By Manganese Oxide (망간산화물에 의한 1-Naphthol의 산화-결합 반응에 따른 반응산물 연구)

  • Lim, Dong-Min;Lee, Doo-Hee;Kang, Ki-Hoon;Shin, Hyun-Snag
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.9
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    • pp.989-996
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    • 2007
  • In this study, abiotic transformation of 1-naphthol(1-NP) via oxidative-coupling reaction and its reaction products were investigated in the presence of Mn oxides. The reaction products were characterized for their relative polarity using solvent extraction experiment and reverse-phase HPLC, and for structure using CCMS and LC/MS, and for absorption characteristics using UV-Vis spectrometry. The reaction products present in aqueous phase were more polar than parent naphthol and comprised of 1,4-naphthoquinon(1,4-NPQ) and oligomers such as dimers and trimers. Hydrophilic component present in water phase after solvent$(CH_2Cl_2)$ extractions was identified as naphthol polymerized products having molecular weight(m/z) ranging from 400 to 2,000, and showed similar UV-Vis. absorption characteristics to that of foil fulvic acid. Transformation of 1,4-NPQ, which is non-reactive to Mn oxide, to the polymerized products via cross-coupling reaction in the presence of 1-NP was also verified. In this experimental conditions(20.5 mg/L, 1-NP, 2.5 g/L $MnO_2$, pH 5), the transformation of 1-NP into the oligomers and polymerized products were about 83% of initial 1-NP concentrations, and more than 30% of the reaction products was estimated to be water insoluble fractions, not extracted by $H_2O$ methanol. Results from this study suggest that Mn oxide-mediated treatment of naphthol contaminated soils can achieve risk reduction through the formation of oligomers md polymer precipitation.

Improving wettability of polyethylene(PE) surface by ion assisted reaction (이온보조반응법에 의한 Polyethylene(PE) 표면의 친수성 증가)

  • 석진우;최성창;장홍규;정형진;최원국;고석근
    • Journal of the Korean Vacuum Society
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    • v.6 no.3
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    • pp.200-205
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    • 1997
  • Surface of polyethylene film was modified by ion assisted reaction in which ion beam is irradiated on polymer in reactive gas environments. Ion (argon and oxygen) beam energy was 1 keV, doses were varied from $1{\times}10^{14}$ to $1{\times}10^{17}$ inons/ $\textrm{cm}^2$, and amount of blowing oxygen from 0 to 4 sccm(ml/min). Wettability was measured by water contact angle measurement, and the surface functionality was analyzed by x-ray photoelectron spectroscopy. The contact angles of water to polyethylene modified by oxygen ion beam only decrease from 95 to degrees, and surface energy was not changed much. The contact angles remarkably decrease to 28 degrees and surface energy increase to 67 erg/ $\textrm{cm}^2$ when the films were modified by argon ion with various ion doses with blowing oxygen gases near the polyethylene surface. Improvement of wettability and surface energy are mainly due to the new functional group formation such as C-O or C=O, which are known as hydrophilic groups from the XPS analysis, and the assisted reaction is very effective to attach oxygen atoms to form functional groups on C-C bond chains of polyethylene.

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The physical properties of the cosmetic hydrogels affected by adding various celluloses (셀룰로오즈 첨가에 따른 미용용 하이드로겔의 물성 연구)

  • Byeon, Hong-Ju;Choi, Won-Seok;Lee, Hyang-Yeol
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.3
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    • pp.702-708
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    • 2018
  • Hydrogels are natural polymer networks that can contain huge quantities of water and many cosmetical ingredients. Their hydrophilic functional groups creates a matrix, which allows high efficacy in delivering active ingredients into the skin. In industry, hydrating properties and strength of the hydrogels are of great interest in manufacturing hydrogel mask packs. We have used the cellulose in various forms such as powder, cotton fiber and cellulase treated cotton fiber to investigate the property changes of cellulose/hydrogel sheets. When 0.1% and 0.3% of cellulose powder were added to hydrogels, tensile strength of hydrogel sheets were decreased by 10% and 14% respectively. Vise versa, when 0.5 ~ 2 cm of cotton fibers were added, tensile strength of hydrogel sheets were significantly increased by about 20%. The hydrogels which contain cotton fibers also gave an excellent moisturizing effect. Especially cellolose/hydrogels containing cellulase-treated cotton fibers showed the best effect on retaining moisture content increasing upto 380% in comparison with the one containing untreated cotton as well as excellent dispersibility.

Polymerization of HEMA by Electron beam Irradiation and Fabrication of Soft contact lens (전자빔조사에 의한 HEMA의 중합과 소프트콘택트렌즈 제조)

  • Hwang, Kwang-Ha;Shin, Joong-Hyeok;Sung, Yu-Jin;Jeong, Keun-Seung;Jun, Jin
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.2
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    • pp.135-141
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    • 2012
  • Purpose: Polymerization of HEMA(2-hydroxyethyl methacrylate) which can be used in the soft contact lens has been performed by using electron beam(EB) irradiation, and examined the best condition for the polymerization. Comparing the physical properties of the contact lenses to the one fabricated by thermal polymerization method, we check the use possibility of the EB irradiation to the fabrication of the soft contact lens. Methods: We investigated the degree of polymerization of the HEMA according to the composition of the monomer, the additive ratio and the dose of electron beam (0~120 kGy). The degree of polymerization was measured depending on the EB dose to research the best synthetic condition under the EB irradiation. The physical properties of the contact lens such as water content(%), oxygen transmissibility(Dk/t) and optical transmittance were analysed by using the FT-IR results with comparing the two different polymerization method (thermal and electron beam polymerization) with same additive ratio. Results: When the dose of electron beam was above 100 kGy, the degree of polymerization of HEMA was above 99% with regardless using cross-linker and initiator. The water content of the lens fabricated by EB method showed 10% higher than the one by the thermal method which was 40%. The lens fabricated by EB method also showed higher oxygen transmissibility(Dk/t) as same with the water content, and showed twice higher value in the lens fabricated by pure HEMA. According to the FT-IR results, hydrophilic property of the lens fabricated by EB method was increased due to increasing the intermolecular hydrogen bonding. It showed above 90% optical transmittance in the visible range of wavelength on the contact lenses fabricated by the both of two different polymerization method. Conclusions: The polymerization of HEMA without cross-linker and initiator was successful above 100 kGy of EB irradiation. Moreover the lens fabricated from the polymer synthesized by pure HEMA with 100 kGy of EB showed the highest water content and oxygen transmissibility. Therefore EB irradiation is another possible method to synthesize the polymer which can be used for the soft contact lens.

Analysis and Safety Assessment of Antioxidants Migrated from Polyethylene and Polypropylene Food Packaging Materials into Food Simulants (폴리에틸렌 및 폴리프로필렌 기구·용기·포장 유래 산화방지제 분석 및 안전성평가)

  • Choi, Heeju;Choi, Jae Chun;Bae, In-Ae;Park, Se-Jong;Kim, MeeKyung
    • Journal of Food Hygiene and Safety
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    • v.32 no.5
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    • pp.424-433
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    • 2017
  • Antioxidants are used in the manufacturing of commercial food packages made of polyolefin plastic such as polyethylene and polypropylene for the purpose to delay the oxidation reaction of the polymer due to oxygen or traces of ozone in the atmosphere. Additives in plastics may be migrated from the packaging materials into foods, thereby presenting a potential health risk to the consumer. Therefore, it is necessary to determine migration level of antioxidants from food packaging materials to foodstuffs in order to take proactive management. In this study, we have developed a method for the analysis of 10 antioxidants, which are butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), Cyanox 2246, 425 and 1790, Irgafos 168, and Irganox 1010, 1330, 3114 and 1076, migrated from the food packaging materials into four food simulants for aqueous, acidic, alcoholic and fatty foods. The antioxidants were determined by reversed-phase high-performance liquid chromatograph-ultraviolet detector with 276 nm after solid-phase extraction with a hydrophilic-lipophilic balance (HLB) cartridge or dilution with isopropanol. The analytical method showed a good linearity of coefficient ($R^2{\geq}0.99$), limits of detection (0.11~0.41 mg/L), and limits of quantification (0.34~1.24 mg/L). The recoveries of antioxidants spiked to four food simulants ranged from 71.3% to 109.4%. The migrated antioxidants in this study were within the safety levels that resulted from the safety assessment by the estimated daily intake to the tolerable daily intake.