• 한국전기전자재료학회논문지
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• 제28권7호
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• pp.462-466
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• 2015

In this paper, we investigated the relations between dispersion of CNTs (carbon nanotubes) and electrical conductivity in the CNT/PVDF (polyvinylidene fluoride) composite film. By adding hydrophobic CNTs as filler into the PVDF matrix, we fabricated hydrophobic and electrically conducting polymer coating film. Dispersion of CNTs in the CNT/PVDF composite film plays a significant role in terms of electrical conductivity and wetting property. Spray coating method was used to form the CNT/PVDF composite films by injecting the dispersed CNTs in the PVDF solution with different weight ratios from 0.7 wt% to 7 wt%. We investigated the electrical properties and contact angles of the CNT/PVDF composite films with the CNT concentration. Finally we discussed the conducting mechanism and feasibility of the CNT/PVDF composite film for the conducting polymer films.

• 한국전기전자재료학회논문지
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• 제29권11호
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• pp.712-715
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• 2016

In this paper, we fabricated flexible CNT/PVDF piezoelectric composite device by introducing CNTs (carbon nanotubes) into PVDF (poly-vinylidene fluoride) solution using spray coating technique. Flexible PEDOT:PSS conducting polymer was used as electrodes. We tried to improve the piezoelectric performance from the CNT/PVDF composite film by increasing the portion of the ${\beta}$-phase PVDF in the film. We confirmed the structural conformation of the CNT/PVDF composite film as a function of CNT concentration by using FT-IR (fourier transform infra-red). As increasing CNT concentration, portion of the ${\beta}$-phase PVDF and resulting piezoelectric performance increased in the CNT/PVDF composite film. We found that CNTs introduced were played as seeds for formation of the ${\beta}$-phase PVDF in the CNT/PVDF composite film and resulting improvement of the piezoelectric performance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.256-256
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• 2013

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process. Charge accumulation and resulting electric field generation mechanism by spray coating method were shown in Fig. 1. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Therefore we can control the performance of the devices fabricated from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• 전기학회논문지
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• 제62권8호
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• pp.1115-1119
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• 2013

The carbon nanotube/poly-vinylidene fluoride (CNT/PVDF) composite films for the use of electronic devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The CNT/PVDF composite films were peeled off from the glass substrate and were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF films and thickness of the films were approximately $20{\mu}m$. The capacitance of the CNT/PVDF films increased dramatically by adding CNTs into the PVDF matrix, and finally saturated approximately 1880 pF. However, the I-V curves didn't show any saturation effect in the CNT concentration range of 0 ~ 0.04 wt%. Therefore we can control the performance of the devices from the CNT/PVDF composite film by adjusting the current level resulted from the CNT concentration with the uniform capacitance value.

• 한국전기전자재료학회논문지
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• 제26권7호
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• pp.550-554
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• 2013

Carbon nanotubes (CNT) / polyvinylidene fluoride (PVDF) piezoelectric composite films for nanogenerator devices were fabricated by spray coating method. When the CNT/PVDF mixture solution passes through the spray nozzle with small diameter by the compressed nitrogen gas, electric charges are generated in the liquid by a triboelectric effect. Then randomly distributed ${\beta}$ phase PVDF film could be re-oriented by the electric field resulting from the accumulated electrical charges, and might be resulted in extremely one-directionally aligned ${\beta}$ phase PVDF film without additional electric field for poling. X-ray diffraction patterns were used to investigate crystal structure of the CNT/PVDF composite films. It was confirmed that they revealed extremely large portion of the ${\beta}$ phase PVDF crystalline in the film. Therefore we could obtain the poled CNT/PVDF piezoelectric composite films by the spray coating method without additional poling process.

• 한국전기전자재료학회논문지
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• 제28권3호
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• pp.196-200
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• 2015

In this paper, we fabricated flexible antenna radiator using the CNT/PVDF (carbon nanotube / polyvinylidene fluoride) composite film. We used polymer film as a matrix material for the flexible devices, and introduced CNTs for adding conductivity into the film resulting in obtaining performances of the antenna radiator. Spray coating method was used to form the CNT/PVDF composite radiator, and pattern formation of the radiator was done by shadow mask during the spray coating process. We investigated the electrical properties of the CNT/PVDF composite films with the CNT concentration, and also estimated the radiator performance. Finally we discuss the feasibility of the CNT/PVDF composite radiator for the flexible antenna.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.736-739
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• 2014

In this paper, we propose a enhanced anti-corrosion property of the ground system by coating the CNT/PVDF composite film on it. Polymer material used for preventing the corrosion of ground system is polyvinylidene fluoride (PVDF), and conducting filler for obtaining conductivity of the composite film is multi-walled carbon nanotubes (MWCNTs). The MWCNTs were dispersed in the organic solvent of methyl ethyl ketone 2-butanone (MEK) with different concentration ratios, and the PVDF was solved in the MEK solvent with constant concentration ratio of 1 wt%. The CNT/PVDF composite solution was perpared by mixing and re-dispersing the CNT solution and the PVDF solution. Finally, the CNT/PVDF composite films were fabricated by the spray coating method using the above composite solution. Electrical conductivity, surface states, and anti-corrosion property of the CNT/PVDF composite films coated on the Cu substrate were evaluated. We found that the CNT/PVDF composite film showed relatively low resistance, hydrophobic surface state, and chemical stability. Consequently, we could improve the anti-corrosion property and maintain the electrical conductivity of the ground system by coating the CNT/PVDF composite film on it.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.620-623
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• 2013

The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately $20{\mu}m$. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the ${\beta}$ phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.

• 한국전기전자재료학회논문지
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• 제29권11호
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• pp.716-719
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• 2016

In this paper, we fabricated flexible CNT/PVDF (carbon nanotube / polyvinylidene fluoride) piezoelectric composite device with flexible poly(3,4-ethylenedioxythiophene) : polystyrene sulfonate (PEDOT:PSS) conducting polymer electrode using spray coating method. We tried to improve the piezoelectric performance from the CNT/PVDF composite film by enhancing electrical conductivity of the PEDOT:PSS electrodes. Electrical conductivity of the PEDOT:PSS electrode was enhanced by dipping it into the EG (ethylene glycol) solvent. Changes of chemical composition of the PEDOT:PSS electrode were analyzed with the dipping time by XPS (x-ray photoelectron spectroscopy) in terms of oxygen (O1s). Finally, Piezoelectric performances such as output voltage and current were measured with the dipping time. We found that enhanced electrical conductivity of the PEDOT:PSS electrodes resulted in improvement of the piezoelectric performance of the CNT/PVDF films.

• Composites Research
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• 제24권6호
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• pp.12-17
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• 2011

자체-센서와 미세 작동기 응용을 위한 CNT와 ITO로 코팅된 나노복합재료의 계면접착 내구성과 전기적 특성을 평가하였다. 나노복합재료의 접착 및 계면 내구성은 반복하중 피로시험에 따른 전기저항도를 측정하여 평가하였다. CNT와 ITO의 고유 전기적 특성으로 인하여 CNT가 코팅된 PVDF 나노복합재료는 ITO가 코팅된 경우보다 다소 낮은 전기저항도를 나타내었으나, 모두 양호한 자체-감지능을 보여주었다. CNT/PVDF와 ITO/PVDF 나노복합재료 모두 계면 내구성은 양호함을 확인하였다. 정적 접촉각 시험을 통해 CNT와 ITO 그리고 PVDF간의 표면에너지, 접착일, 그리고 퍼짐계수를 평가하여 계면 내구성과 의 상호 관련성을 확인하였다. 수용액에서 CNT와 ITO로 코팅된 PVDF 시편의 최적의 작동성은 주파수와 전압을 달리하여 레이져 변위센서를 사용한 연신율 변화로 측정하였다. 작동된 두 나노복합재료들의 연신율은 주파수가 증가함에 따라 감소하며, 반면에 전압의 증가에 따라 상승하였다. 각 나노복합재료의 나노구조 및 고유의 전기적 특성으로 인하여, CNT/PVDF가 ITO/PVDF 보다 자체-감지 및 작동기로서 더 적합하다는 것을 알 수 있었다.