• 분석과학
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• 제27권5호
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• pp.228-233
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• 2014

전기방사된 나노섬유는 구조 및 비교적 손쉬운 제조공정으로 의료용 재료분야의 활용이 늘어나고 있다. 제조된 나노섬유는 블럭공중합체의 PCL-PEG diamin block copolymer의 혼합 비가 높을수록 말단에 결합된 아민기의 비가 높아진다. 생분해성 고분자인 폴리카프로락톤(Poly(e-caprolactone,PCL)과 폴리카프로락톤-폴리에틸렌글리콜-아민(Poly(e-caprolactone)-Poly(ethylen glycol-$NH_2$))의 블럭공중합체를 혼합한 비율을 조절하여 전기방사법으로 방사함으로써, 세포와의 친화도를 조절하였다. PEG and amine의 비율과 콜라겐의 영향으로 손상된 세포의 성장을 촉진시키는 효과를 기대할 수 있는 생분해성 복합 나노섬유를 제작 및 특성 분석하였다.

• 한국가시화정보학회지
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• 제16권3호
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• pp.40-46
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• 2018

The surface structure of the electrospun polymer fibers depends on the polymer concentration, the type of solvent used, applied voltage and so on. To make a desired surface, it is important to understand the effects of the physicochemical properties to form a stable Taylor cone and jet dispensation. We observed the formation of Taylor cone and a consequent structure of fiber by controlling the parameters of applied voltage, solution concentration, solvent and collector effectively. Once the surfaces were fabricated, the structures were analyzed using optical imaging technologies. As the solution concentration was increased, the smooth fibers were formed. In addition, different solvent ratios determined the viscosity and the surface tension of solutions. As a result, with decreased viscosity and increased surface tension, thin fibers were obtained by electrospinning. Furthermore the aligned nanofiber was successfully created by using drum collector.

• 한국발생생물학회지:발생과생식
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• 제24권2호
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• pp.135-147
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• 2020

Polyvinylidene fluoride (PVDF) is a stable and biocompatible material that has been broadly used in biomedical applications. Due to its piezoelectric property, the electrospun nanofiber of PVDF has been used to culture electroactive cells, such as osteocytes and cardiomyocytes. Here, taking advantage of the piezoelectric property of PVDF, we have fabricated a PVDF nanofiber scaffolds using an electrospinning technique for differentiating human embryonic stem cells (hESCs) into neural precursors (NPs). Surface coating with a peptide derived from vitronectin enables hESCs to firmly adhere onto the nanofiber scaffolds and differentiate into NPs under dual-SMAD inhibition. Our nanofiber scaffolds supported the differentiation of hESCs into SOX1-positive NPs more significantly than Matrigel. The NPs generated on the nanofiber scaffolds could give rise to neurons, astrocytes, and oligodendrocyte precursors. Furthermore, comparative transcriptome analysis revealed the variable expressions of 27 genes in the nanofiber scaffold groups, several of which are highly related to the biological processes required for neural differentiation. These results suggest that a PVDF nanofiber scaffold coated with a vitronectin peptide can serve as a highly efficient and defined culture platform for the neural differentiation of hESCs.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.148-155
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• 2015

Electrospun $LaCoO_3$ perovskite nanofibers were produced for the air electrode in Zn-air rechargeable batteries using electrospinning technique with sequential calcination. The final calcination temperature was varied from 500 to $800^{\circ}C$ in order to determine its effect on the physical and electrochemical properties of the prepared $LaCoO_3$ perovskite nanofibers. The surface area of the electrospun $LaCoO_3$ perovskite nanofibers were observed to decrease with increasing final calcination temperature. Electrospun $LaCoO_3$ perovskite nanofibers calcined with final calcination temperature of $700^{\circ}C$ had the best electrocatalytic activity among the prepared perovskite nanofibers.

• Carbon letters
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• 제10권3호
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• pp.217-220
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• 2009

In this study, porous electrospun carbon fibers were prepared by electrospinning with PAN and $MgCl_2$, as a MgO precursor. MgO was selected as a substrate because of its chemical and thermal stability, no reaction with carbon, and ease of removal after carbonization by dissolving out in acidic solutions. $MgCl_2$ was mixed with polyacrylonitrile (PAN) solution as a precursor of MgO with various weight ratios of $MgCl_2$/PAN. The average diameter of porous electrospun carbon fibers increased from 1.3 to 3 ${\mu}m$, as the $MgCl_2$ to PAN weight ratio increased. During the stabilization step, $MgCl_2$ was hydrolyzed to MgOHCl by heat treatment. At elevated temperature of 823 K for carbonization step, MgOHCl was decomposed to MgO. Specific surface area and pore structure of prepared electrospun carbon fibers were decided by weight ratio of $MgCl_2$/PAN. The amount of hydrogen storage increased with increase of specific surface area and micropore volume of prepared electrospun carbon fibers.

• 공업화학
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• 제19권5호
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• pp.484-490
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• 2008

폴리비닐피로디온을 서로 다른 끓는점, 유전상수, 쌍극자모멘트를 갖는 다양한 용매(메탄올, 에탄올, 2-프로판올, 부탄올, 아세톤, 메틸렌클로라이드 및 DMF)에 용해시켜 전기방사를 시도하여 섬유의 특성을 연구하였다. 전기 방사된 폴리비닐피로디온은 방사용액의 점도, 전기전도도 및 표면장력에 영향을 받는다. 점도가 $0.114kg/m{\cdot}s$ 이상, 전기전도도는 1.02 mS/m 이상, 표면장력은 30.0 mN/m 이하에서 섬유가 형성되었다. 에탄올 용매계에서 폴리비닐피로디온의 평균직경은 인가전압이 10 kV에서 20 kV 증가시킴에 따라 1710에서 5454 nm까지 증가하였다.

• 대한기계학회논문집B
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• 제29권4호
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• pp.512-518
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• 2005

Polymeric fibers with nanometer-scale diameters are produced by electrospinning. When the electrical forces at the surface of a polymer solution or melt overcome the surface tension then electrospinning occurs. Polycarbonate has been electrospun. Electrospun fibers are observed by scanning electron microscopy and transmission electron microscopy. The surface morphology of e-spun fiber has been studied by many variables that are involved in different polymer concentrations, solvent mixing ratios and ambient parameters. The average diameters of the electrospun fibers range from 200 nm to 4,570 nm when the PC concentration is decreasing from 15.5\;wt{\%}\;to\;25\;wt{\%}.$ The higher concentration of the polymer solution makes the fibers thicker due to preventing the fiber stretching. With respect evaporation effects, the solvent mixing ratios cause significant changes of the fiber size distribution. As a matter of fact the fiber diameter steadily increases with increasing amount of DMF until the solvent mixture is at THF:DMF ratio of 60:40.

• 한국의류학회지
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• 제35권11호
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• pp.1297-1308
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• 2011

This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

• Macromolecular Research
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• 제16권3호
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• pp.212-217
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• 2008

PVDF ($Kynar^{(R)}$ 761) nanofibers were made by electrospinning with an external voltage of 6-10 kV, a traveling distance of 7-15 cm and a flow rate of 0.4-1 mL/h. Although the mean diameter of the fibers has not changed significantly, the conditions affected the change in diameter distribution. This was attributed to interactions, both attraction and repulsion, between the positive charges on the polymer solutions and the electrically grounded collector. Higher voltages and traveling distance increased the level of attraction between the positive charge on the polymer solution and the electrically grounded collector, resulting in a narrow diameter distribution, In addition, a high flow rate allowed a high population of uniformly charged solutions to travel to the grounded collector, which resulted in a narrow diameter distribution. The optimum conditions for electrospinning of PVDF in DMAc/acetone (3/7 by wt) were a collector voltage of 6 kV, a syringe tip to collector of 7 cm, a flux rate of 0.4 mL/h and 10 kV, 10 cm, 1 mL/h, Since PVDF is widely used as a filtration membrane, it was electrospun on a PET support with a rotating drum as a grounded collector. Surprisingly, some straight nanofibers were separated from the randomly deposited nanofibers. The straight nanofiber area was transparent, while the randomly deposited nanofiber area was opaque. Both straight nanofibers and aligned nanotibers could be obtained by manipulating the PET drum collector. These phenomena were not observed when the support was changed to an Al sheet. This suggests that a pseudo dual collector was generated on the PET sheet. No negative charge was created because the PET sheet was not a conductive material. However, less charge was created when the sheet was not perfectly attached to the metal drum. Hence, the nanotibers jumped from one grounded site to the nearest one, yielding a straight nanofiber.

• Carbon letters
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• 제8권4호
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• pp.313-320
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• 2007

In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed under different heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicated that stabilization and carbonization processes with different temperatures and heating rates significantly influenced the chemical and morphological characteristics as well as the thermal properties of the stabilized and then subsequently carbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of a carbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization and carbonization processes.