• Title/Summary/Keyword: PVP

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Fabrication of Organic TFT wi th PVP Gate Insulating layer (PVP 게이트 절연막을 이용한 유기박막트랜지스터 제작)

  • Jang Ji-Geun;Seo Dong-Gyoon;Lim Yong-Gyu;Chang Ho-Jung;Oh Myung-Hwan
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • 2005.09a
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    • pp.83-88
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    • 2005
  • 유기 절연층을 갖는 유기 박막트랜지스터 (organic TFT)를 제작하여 소자 성능을 조사하였다. 유기 절연층의 형성에서는 polyvinyl 계열의 PVP(poly-4-vinylphenol)와 PVT(polyvinyltoluene)를 용질로, PGMEA (propylene glycol mononethyl ether acetate)를 용매로 사용하였다. 또한, 열경화성 수지인 poly(melamine-co-formaldehyde)를 경화제로 사용하여 유기 절연층의 cross-link 를 시도하였다. MIM 구조로 유기 절연층의 특정을 측정한 결과, PVT는 PVP에 비해 절연 특성이 떨어지는 경향을 보였다. 게이트 절연막의 제작에서 PVP를 cobpolymer 방식과 cross-linked 방식으로 실험 해 본 결과, cross-link 방식에서 낮은 누설전류 특성을 나타내었다. OTFT 제작에서는 PVP를 용질로, poly(melanine-co-formaldehyde)를 경화제로 사용한 cross-linked PVP 를 게이트 절연막으로 이용하였다. PVP copolymer($20\;wt\%$)에 $10\;wt\%$ poly(melamine- co-formaldehyde)를 혼합한 cross-linked PVP 를 게이트 절연막으로 사용하여 top contact 구조의 OTFT를 제작한 결과 약 $0.23\;cm^2/Vs$의 정공 이동도와 약 $0.4{\times}10^4$의 평균 전류점멸비를 나타내었다.

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Preparation and Characterization of Poly(vinyl alcohol)/Poly(N-vinylpyrrolidone)/Glycerin/Chitosan Hydrogels by Radiation (방사선 가교에 의해 제조된 Poly(vinyl alcohol)/Poly(N-vinylpyrrolidone)/글리세린/키토산 하이드로겔의 제조 및 특성)

  • 박경란;노영창
    • Polymer(Korea)
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    • v.26 no.6
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    • pp.792-802
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    • 2002
  • In this study, hydrogels from mixtures of poly (vinyl alcohol) (PVA)/poly(N-vinylpyrrolidone) (PVP)/glycerin/chitosan were prepared by γ-ray irradiation and the mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the applicability of these for wound dressing. Then PVA:PVP was weight ratio of 6 : 4, the concentration of chitosan was 0.3 wt%, the concentration of glycerin was in the range of 0∼5 wt%t. The solid concentration of PVA/PVP/glycerin/chitosan solution was 15 wt%. Gamma irradiation doses of 25, 35, 50, and 60 kGy were exposed to a mixture of PVA/PVP/glycerin/chitosan to evaluate the effect of irradiation dose. Gel content and gel strength increased as glycerin concentration in PVA/PVP/glycerin/chitosan decreased, and as irradiation dose increased. Swelling degree increased as glycerin concentration in PVA/PVP/glycerin/chitosan increased, and as irradiation dose decreased. The glycerin in PVA/PVP/glycerini/chitosan hydrogel prevented the transformation of shape. These hydrogel dressings had better curing effect than vaseline gauge.

Improvement of Electrical and Mechanical Characteristics of Organic Thin Film Transistor with Organic/Inorganic Laminated Gate Dielectric (유연성 유기 박막트랜지스터 적용을 위한 다층 게이트 절연막의 전기적 및 기계적 특성 향상 연구)

  • Noh, H.Y.;Seol, Y.G.;Kim, S.I.;Lee, N.E.
    • Journal of the Korean institute of surface engineering
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    • v.41 no.1
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    • pp.1-5
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    • 2008
  • In this work, improvement of mechanical and electrical properties of gate dielectric layer for flexible organic thin film transistor (OTFT) devices was investigated. In order to increase the mechanical flexibility of PVP (poly(4-vinyl phenol) organic gate dielectric, a very thin inorganic $HfO_2$ layers with the thickness of $5{\sim}20nm$ was inserted in between the spin-coated PVP layers. Insertion of the inorganic $HfO_2$ in the laminated organic/inorganic structure of PVP/$HfO_2$/PVP layer led to a dramatic reduction in the leakage current compared to the pure PVP layer. Under repetitive cyclic bending, the leakage current density of the laminated PVP/$HfO_2$/PVP layer with the thickness of 20-nm $HfO_2$ layer was not changed, while that of the single PVP layer was increased significantly. Mechanical flexibility tests of the OTFT devices by cyclic bending with 5 mm bending radius indicated that the leakage current of the laminated PVP/$HfO_2$(20 nm)/PVP gate dielectric in the device structure was also much smaller than that of the single PVP layer.

Effect of Molecular Weights and Mixture Ratios of Polyvinylpyrrolidone on the Bioavailability of Ipriflavone Solid Dispersion (이프리플라본 고체분산체의 생체이용률에 미치는 폴리비닐피롤리돈의 분자량 및 혼합비율의 영향)

  • Jeong, Je-Kyo;Khang, Gil-Son;Rhee, John-M.;Shin, Ho-Chul;Lee, Hai-Bang
    • Journal of Pharmaceutical Investigation
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    • v.30 no.4
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    • pp.235-239
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    • 2000
  • Ipriflavone (3-phenyl-7-isopropoxy-4H-1-benzopyran-4-one, IP) is a well-known antiosteoporotic drug with poor bioavailability. In the previous study, we reported that the IP formulation prepared by spray-drying method with polyvinylpyrrolidone (PVP) (SIP) was very effective in improving the bioavailability of IP. In this study, we examined the effects of molecular weight and mixture ratios of PVP to IP on the systemic absorption of IP following oral administration of SIP at a dose of 50 mg/kg to rats. In the effect of molecular weight, the Cmax of spray-dried IP with PVP K30 (SIP-K30) was significantly higher than those of spray-dried IP with PVP 360 (SIP-360), spray-dried IP with PVP K90 (SIP-K90), and spray-dried IP with PVP K17 (SIP-K17) (p<0.05). The AUC of SIP-K30 was about 2, 3, and 5.5 times higher than those of SIP-360, SIP-K90, and SIP-K17, respectively. The AUC value of SIP-K30 was significantly greater than those of SIP-K17 and SIP-K90 (p<0.05) except for SIP-360. In the ratio of PVP K30 to drug, the $C_{max}$ and the AUC value of 3 : 7 IP-PVP solid dispersion were similar to those of 5 : 5 IP-PVP and significantly higher than those of the other solid dispersions (p<0.05). It was concluded that the spray-dried IP with PVP K30 at the ratio of 3:7 (w/w) was the best formulation for improving the bioavailability of IP.

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Formation and Characterization of Polyvinyl Series Organic Insulating Layers (폴리비닐 계열 유기절연막 형성과 특성평가)

  • Jang Ji-Geun;Jeong Jin-Cheol;Shin Se-Jin;Kim Hee-Won;Kang Eui-Jung;Ahn Jong-Myong;Seo Dong-Gyun;Lim Yong-Gyu;Kim Min-Young
    • Journal of the Semiconductor & Display Technology
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    • v.5 no.1 s.14
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    • pp.39-43
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    • 2006
  • The polyvinyl series organic films as gate insulators of thin film transistor(TFT) have been processed and characterized on the polyether sulphone (PES) substrates . The poly-4-vinyl phenol(PVP) and polyvinyl toluene (PVT) were used as solutes and propylene glycol monomethyl ether acetate(PGMEA) as a solvent in the formation of organic insulators. The cross-linking of organic insulators was also attempted by adding the thermosetting material, poly (melamine-co-formaldehyde) as a hardener in the compound. The electrical characteristics measured in the metal-insulator-metal (MIM) structures showed that insulating properties of PVP layers were generally superior to those of PVT layers. Among the layers of PVP series; copolymer PVP(10 wt%), 5wt% cross-linked PVP(10 wt%), copolymer PVP(20 wt%), 5 wt% cross-linked PVP(20 wt%) and 10 wt% cross-linked PVP(20 wt%), the 10 wt% cross-linked PVP(20 wt%) layer showed the lowest leakage current of 1.2 pA at ${\pm}10V$. The ms value of surface roughness and the capcitance per unit area are 2.41 and $1.76nF/cm^2$ in the case of 10 wt% cross-linked PVP(20 wt%) layer, respectively.

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Albumin-Crosslinked PVP Hydrogel as a Gastric Retention Platform (위내체류를 목적으로 한 알부민 가교 PVP 하이드로겔의 팽윤특성)

  • Shim, Chang-Koo;Yeo, So-Hyeon
    • Journal of Pharmaceutical Investigation
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    • v.23 no.3
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    • pp.145-153
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    • 1993
  • Retaining a drug in the stomach by some means is sometimes necessary to extend the G1 absorption time of the drug more than 6-8 hrs. Hydrogel has often been examined for its feasibility as a dosage form, so called platform, that could be retained in the stomach due to its excellent swelling properties in the gastric fluid. In this study, polyvinylpyrrolidone (PVP) hydrogel crosslinked by albumin or acrylated albumin was synthesized in a tablet form and evaluated for its possibility as the platform. The synthesis of the hydrogel was performed by $^{60}Co\;{\gamma}-ray$ irradiation of N-vinyl-2-pyrrolidone (monomer) in the presence of a crosslinking agent: aqueous solution of albumin or acrylated albumin. Synthetic conditions such as radiation dose, dose rate and concentration of crosslinking agent were varied in order to optimize the swelling and mechanical properties of the hydrogels. Degree of swelling of albumin-crosslinked PVP (Al-PVP) was highly dependent on radiation dose, dose rate and albumin concentration: it was decreased as they increased. On the other hand, that of acrylated albumin-crosslinked PVP (Acryl-PVP) was almost independent on them except dose rate: it was decreased as the radiation dose rate increased. The compressive strength of the two hydrogels was decreased as the dose rate increased. Digestion of both PVP in artificial gastric fluid containing pepsin was delayed by the ${\gamma}-ray$ irradiation. In conclusion, Al-PVP and Acry-PVP with diverse swelling and mechanical properties could be obtained by controlling synthetic conditions, mainly the irradiation dose rate.

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Survival and In Vitro Development of Immature Bovine Oocytes Cryopreserved by Vitrification

  • Yang, Byoung-Chul;Im, Gi-Sun;Chang, Won-Kyong;Lee, Yun-Keun;Oh, Sung-Jong;Jin, Dong-Il;Im, Kyong-Sun;Lee, Chang-Kyu
    • Asian-Australasian Journal of Animal Sciences
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    • v.16 no.1
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    • pp.23-28
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    • 2003
  • The present study was undertaken to investigate the effects of PVP concentration and exposure temperature to vitrification solution on the post-thaw survival, in vitro maturation and development of immature bovine oocytes (germinal vesicle stage). The vitrification solution (VS) consisted of 40% ethylene glycol (EG)+0.5 M sucrose (S)+10% FBS. PVP was added to VS: 0%, 5% or 10%. The cumulus-oocyte complexes (COCs) were diluted in VS as one step, after 2 min the COCs were loaded in straw and vitrified by direct immersion into liquid nitrogen. For thawing, the straws were plunged into $30^{\circ}C$ water bath for 10s. After thawing, the oocytes were diluted in 0.5 M (in DPBS with 10% FBS) sucrose solution for 5 min. The survival rate (FDA-test and trypan blue) of immature bovine oocytes was measured. The survival rate was higher in 5% PVP (91.5%) than in 0% (64.2%) or in 10% PVP (79.7%). The proportion of metaphase II formation was 69.35% in control (no vitrified COCs), 9.3% in 40% EG+0.5 M S+0% PVP and 21.05% in 40% EG+0.5 M S+5% PVP (p<0.05). The effect of room temperature ($25^{\circ}C$ for 10 min) and cold temperature ($4^{\circ}C$ for 10 min) on COCs were determined in this study. After IVF, the cleavage and blastocysts rate of oocytes exposed to room temperature and cold temperature in VS+5% PVP was significantly different (2 cell: 63.20% vs 37.97%, blastocysts: 18.40% vs 2.53%). The cleavage rates of frozen-thawed oocytes were 20.53% with PVP and 22.13% without PVP (p>0.05). Two out of 151 oocytes (1.32%) developed to blastocyst stage after frozen-thawed with 5% PVP (p>0.05). Development of oocytes after frozen-thawing to the 2 cell were not significantly affected with or without PVP following IVF. However, the vitrification of immature bovine oocytes with PVP maintained the ability to develop to the blastocyst stage after IVM-IVF and IVC, while no blastocysts were obtained from oocytes vitrified without PVP. These results suggested that PVP has a protective role for vitrification of immature bovine oocytes as far as survival is concerned, however, the protection was not sufficient enough to support blastocyst formation.

Properties of a Nanosilver-Silica Composite Synthesized with Different Molecular Weights and Polyvinylpyrrolidone Concentrations (PVP 분자량과 농도 변화에 따른 은-실리카 나노복합체의 특성에 관한 연구)

  • Son, Eun-Jong;Jeong, Sung-Hoon
    • Textile Science and Engineering
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    • v.54 no.5
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    • pp.309-314
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    • 2017
  • Well-dispersed nanosilver particles were synthesized by a chemical reduction method, where silica was treated with amino groups, mercapto groups, and polyvinylpyrrolidone (PVP) as a dispersant. Transmission electron microscopy (TEM) images showed that both the concentration and the molecular weight of PVP considerably affected the size of the silver nanoparticles. The average size of the silver nanoparticles prepared with amino-treated silica increased with increasing PVP concentration, whereas the size of the silver nanoparticles prepared with mercapto-treated silica was not affected by the PVP concentration. As the molecular weight of PVP increased, the average size of the silver nanoparticles also increased. The number of silver particles formed with mercapto-treated silica was larger, and the size distribution was narrower than those formed from aminotreated silica.

Preparation of Ag/PVP Nanocomposites as a Solid Precursor for Silver Nanocolloids Solution

  • Hong, Hyun-Ki;Park, Chan-Kyo;Gong, Myoung-Seon
    • Bulletin of the Korean Chemical Society
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    • v.31 no.5
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    • pp.1252-1256
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    • 2010
  • A polyvinylpyrrolidone (PVP)/Ag nanocomposites was prepared by the simultaneous thermal reduction and radical polymerization route. The in situ synthesis of the Ag/PVP nanocomposites is based on the finding that the silver n-propylcarbamate (Ag-PCB) complex can be directly dissolved in the NVP monomer, and decomposed by only heat treatment in the range of 110 to $130^{\circ}C$ to form silver metal. Silver nanoparticles with a narrow size distribution (5 - 40 nm) were obtained, which were well dispersed in the PVP matrix. A successful synthesis of Ag/PVP nanocomposites then proceeded upon heat treatment as low as $110^{\circ}C$. Moreover, important advantages of the in situ synthesis of Ag/PVP composites include that no additives (e.g. solvent, surface-active agent, or reductant of metallic ions) are used, and that the stable silver nanocolloid solution can be directly prepared in high concentration simply by dissolving the Ag/PVP nanocomposites in water or organic solvent.

Morphology control in PVDF membranes using PEG/PVP additives and mixed solvents

  • Rajabi, Shima;Khodadadi, Foroogh;Mohammadi, Toraj;Tavakolmoghadam, Maryam;Rekabdar, Fatemeh
    • Membrane and Water Treatment
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    • v.11 no.4
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    • pp.237-245
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    • 2020
  • The effects of the mixed two solvents, Dimethylacetamide (DMAc) and Dimethylformamide (DMF), and Polyethylene glycol (PEG) and Polyvinylpyrrolidone (PVP) as additives on performance of Polyvinylidene fluoride (PVDF) membranes were studied. Initially, PEG200 was used as a primary additive at fixed percentage of 5% wt. PVP was then blended with PEG200 in different concentrations. PVDF and DMAc were used as polymer and solvent in the casting solutions, respectively. To control the diffusion rate of PVP in the presence of PEG200 and PVP blend, mixtures of DMAc and DMF were used as the mixed solvent in the casting solutions. Asymmetric PVDF membranes were prepared via phase inversion process in a water bath and the effects of two additives and two solvents on the membrane morphology, pure water flux (PWF), hydrophilicity and rejection (R) were investigated. Attenuated Total Reflection Fourier Transform Infrared Spectra (ATR-FTIR) analysis was used to show the residual PVP on the surface of the membranes. Atomic Force Microscopy (AFM) was utilized to determine roughness of membrane surface. The use of mixed solvents in the casting solution resulted in reduction of PVP diffusion rate and increment of PEG diffusion rate. Eventually, PWF and R values reduced, while porosity and hydrophilicity increased.