• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.9.2-9.2
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• 2008

• 폴리머
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• 제29권2호
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• pp.204-210
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• 2005

플라스틱 디스플레이 기판용으로 사용하기 위하여 무색, 투명하면서 유연성, roll-to-roll 공정, 내열성과 저 열팽창계수 특성을 갖출 수 있는 폴리이미드에 대한 연구를 하였다. 3,3',4,4'-oxydiphthalic anhydride(ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), sulfonyldianiline(3-SDA), aminophenoxybenzene(TPE-p, TPE-q, TPE-r)과 bis[4-(3-aminophenoxy)phenyl]sulfone(m-BAPS) 등을 사용하여 무색 투명한 폴리이미드를 합성하고 광학적 특성을 UV spectrophotometer, colormeter와 hazemeter를 이용하여 측정하였다. 열팽창계수(CTE)를 낮추기 위하여 층상실리케이트로 나노복합화하였다. 무색투명한 폴리이미드 필름은 440 nm에서 $89\%$ 이상의 광투과도와 yellow index(YI) 값이 7 이하의 우수한 광학 특성을 보였다. 나노복합화한 폴리이미드 필름은 층상실리케이트가 효과적으로 박리되어 층상실리케이트의 함유량이 증가함에 따라 열팽창계수가 감소하는 효과를 보였다.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.777-782
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• 2008

초음파 중합법을 이용하여 pyrrole을 중합시킴으로써 polypyrrole 나노입자를 합유하는 메조포러스 $TiO_2$ 박막을 합성하였다. 메조포러스 $TiO_2$ 박막을 만들기 위한 $TiCl_4$-계면활성제 용액에 pyrrole을 넣어주고 초음파 중합시킴으로써 용액 내에 polypyrrole 나노입자들이 잘 분산된 형태로 만들어졌다. 이 용액을 이용하여 spin-coating과 열처리를 함으로써 polypyrrole 나노입자를 합유하는 메조포러스 $TiO_2$ 박막을 제조하였다. 열처리 후에도 기공 구조는 잘 유지되었으며, polypyrrole 나노입자들이 박막 내에 잘 분산되었다. 주형물질인 계면활성제의 종류와 pyrrole의 양을 조절함으로써, 합성된 박막의 기공 크기와 빛의 흡광도를 조절하였다.

• 공업화학
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• 제17권5호
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• pp.527-531
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• 2006

본 연구는 커패시터(capacitor) 등의 유전재료로서 응용이 가능한 고분자로 코팅된 무기입자 및 이를 이용하여 제조된 유전율이 높은 폴리이미드(polyimide; PI) 나노복합재에 관한 것이다. 무기입자로는 높은 유전상수를 가지는 barium titanate(BT)를 선정하였고, 이를 유기 고분자인 나일론 6으로 표면 코팅하여 매트릭스 고분자인 폴리이미드와의 친화력을 향상시켰다. FT-IR과 TEM을 통하여 5 nm 두께의 고분자 셀(shell)이 형성된 친유기화된 무기입자(BTN)를 확인하였으며, 나일론 6이 코팅된 BT의 내경과 외경의 비, 그리고 $\alpha$와의 관계를 나타낸 모식도를 통해 고분자 코팅 두께를 조절할 수 있음을 제안하였다. 제조된 BTN과의 복합화를 통하여 폴리아믹산 나노복합용액을 제조하였으며, 이를 탈수 고리화하여 열적 및 전기적 특성이 우수한 폴리이미드 나노복합필름을 제조하였다. SEM을 통하여 BTN이 매트릭스 고분자 내에 균일 분산상을 형성함을 확인하였으며, TGA와 전기적 측정을 통하여 BTN의 함량에 따른 폴리이미드 나노복합필름의 열안정성 지수, 적분 열분해 온도 및 유전율의 변화를 각각 조사하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.54-54
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• 2011

The demand for low-friction, wear and corrosion resistant components, which operate under severe conditions, has directed attentions to advanced surface engineering technologies. The Filtered Vacuum Arc Cathode Deposition (FVACD) process has demonstrated atomically smooth surface at relatively high deposition rates over large surface areas. Preparation of Ti-Si-C-N nanocomposite coatings on (100) Si and stainless steel substrates with tetramethylsilane (TMS) gas pressures to optimize the film preparation conditions. Ti-S-C-N coatings were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, Rockwell C indentation and ball-on-disk wear tests. The XRD results have confirmed phase formation information of TiSiCN coatings, which shows mixing of TiN and TiC structure, corresponding to (111), (200) and (220) planes of TiCN. The chemical composition of the film was investigated by XPS core level spectra. The binding energy of the elements present in the films was estimated using XPS measurements and it shows present of elemental information corresponding to Ti2p, N1s, Si 2p and C1. Film hardness and elastic modulus were measured with a nano-indenter, and film hardness reached 40 GPa. Tribological behaviors of the films were evaluated using a ball-on-disk tribometer, and the films demonstrated properties of low-friction and good wear resistance.

• 한국분말재료학회지
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• 제8권3호
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• pp.201-206
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• 2001

$>LaMnO_3$$(La, Sr)MO_3$, and $(La, Sr)MO_3/YSZ$ gel films were deposited by spin-coating technique on scandium-doped zirconia (YSZ) substrate using the precursor solution prepared from $La(O-i-C_3H_7)_3$, $Co(CH_3COO)_2$or $Mn(O-i-C_3H_7)_2$,2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, the electrochemical cells, $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ were fabricated. The effect of polyethylene glycol on the microstructure evolution of $$LaCoO_3and $LaMnO_3$thin films was investigated, and NOx decomposition characteristics of the electrochemical cells were investigated at $500^{\circ}C$ to $600^{\circ}C$. By applying a direct current to the $(La, Sr)MnO_3{\mid}ScSZ{\mid}Pt$ electrochemical cell, good NOx conversion rate could be obtained relatively at low current value even if excess oxygen is included in the reaction gas mixture.

• Smart Structures and Systems
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• 제12권1호
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• pp.55-71
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• 2013

Structural health monitoring (SHM) is vital for detecting the onset of damage and for preventing catastrophic failure of civil infrastructure systems. In particular, piezoelectric transducers have the ability to excite and actively interrogate structures (e.g., using surface waves) while measuring their response for sensing and damage detection. In fact, piezoelectric transducers such as lead zirconate titanate (PZT) and poly(vinylidene fluoride) (PVDF) have been used for various laboratory/field tests and possess significant advantages as compared to visual inspection and vibration-based methods, to name a few. However, PZTs are inherently brittle, and PVDF films do not possess high piezoelectricity, thereby limiting each of these devices to certain specific applications. The objective of this study is to design, characterize, and validate piezoelectric nanocomposites consisting of zinc oxide (ZnO) nanoparticles assembled in a PVDF copolymer matrix for sensing and SHM applications. These films provide greater mechanical flexibility as compared to PZTs, yet possess enhanced piezoelectricity as compared to pristine PVDF copolymers. This study started with spin coating dispersed ZnO- and PVDF-TrFE-based solutions to fabricate the piezoelectric nanocomposites. The concentration of ZnO nanoparticles was varied from 0 to 20 wt.% (in 5 % increments) to determine their influence on bulk film piezoelectricity. Second, their electric polarization responses were obtained for quantifying thin film remnant polarization, which is directly correlated to piezoelectricity. Based on these results, the films were poled (at 50 $MV-m^{-1}$) to permanently align their electrical domains and to enhance their bulk film piezoelectricity. Then, a series of hammer impact tests were conducted, and the voltage generated by poled ZnO-based thin films was compared to commercially poled PVDF copolymer thin films. The hammer impact tests showed comparable results between the prototype and commercial samples, and increasing ZnO content provided enhanced piezoelectric performance. Lastly, the films were further validated for sensing using different energy levels of hammer impact, different distances between the impact locations and the film electrodes, and cantilever free vibration testing for dynamic strain sensing.

• 폴리머
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• 제37권2호
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• pp.225-231
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• 2013

순수한 점토 5 wt%를 포함하는 poly(vinyl alcohol)(PVA) 나노 복합체 필름을 수용액상에서 합성하였다. 합성된 PVA 복합체 필름에는 구조적으로 각각 다른 사포나이트(SPT), 몬모릴로나이트(MMT), 헥토라이트(SWN), 수용성 벤토나이트(PGV) 및 마이카(Mica) 등의 점토를 사용하였다. 이처럼 여러 가지 순수한 점토가 포함된 PVA 복합체 필름에 대해 열적-광학적 성질 및 모폴로지를 평가하였으며, 전자 현미경을 통해 관찰된 PVA 복합체 필름의 나노 구조에서는 점토가 매트릭스에 잘 분산된 부분도 있었지만, 일부에서는 뭉친 부분도 발견되었다. 점토를 사용한 PVA 복합체 필름의 경우에 열적 성질이나 가스 차단성을 증가시키는 데에는 매우 효과적이었지만, 이와는 반대로 광학 투명성에서는 그렇지 못하였다.

• Macromolecular Research
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• 제16권4호
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• pp.308-313
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• 2008

A simple strategy was developed based on polyelectrolyte/silver nanocomposite to obtain humidity-sensitive membranes. The major component of a humid membrane is the polyTEAMPS/silver nanocomposite obtained by thermal heating the mixture of a polyelectrolyte and silver isopropylcarbamate complex. Humidity sensors prepared from polyTEAMPS/silver (w/w=100/0 and 100/6) nanocomposites had an average impedance of 292, 8.83 and $0.86\;k{\Omega}$, and 5,327, 140 and $0.93\;k{\Omega}$ at 30,60 and 95% relative humidity (RH), respectively. Hysteresis, temperature dependence and response time were also measured. Activation energies and complex impedance spectroscopy of the various components of the polyelectrolyte/silver nanocomposite films were examined for the humidity-sensing membrane.

• Advances in nano research
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• 제14권4호
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• pp.355-362
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• 2023

Physical exercise, especially intense exercise and high intensity interval training (HIIT) by trampoline, can lead to muscle injuries. These effects can be reduced with intelligent products made of nanocomposite materials. Most of these nanocomposites are polymers reinforced with silicon dioxide, alumina, and titanium dioxide nanoparticles. This study presents a polymer nanocomposite reinforced with silica. As a result of the rapid reaction between tetraethyl orthosilicate and ammonia in the presence of citric acid and other agents, silica nanostructures were synthesized. By substituting bis (4-amino phenoxy) phenyl-triptycene in N, N-dimethylformamide with potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C, the diamine monomer bis (4-amino phenoxy) phenyl-triptycene is prepared. We synthesized a new polyaromatic (imide) with triptycene unit by sol-gel method from aromatic diamines and dianhydride using pyridine as a condensation reagent in NMP. PI readily dissolves in solvents and forms robust and tough polymer films in situ. The FTIR and NMR techniques were used to determine the effects of SiO₂ on the sol-gel process and the structure of the synthesized nanocomposites. By using a simultaneous thermal analysis (DTA-TG) method, the appropriate thermal operation temperature was also determined. Through SEM analysis, the structure, shape, size, and specific surface area of pores were determined. Analysis of XRD results is used to determine how SiO₂ affects the crystallization of phases and the activation energy of crystallization.