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조재환,Yadav, Santosh Kumar,Mahapatra, Sibdas Singha,Cho, Jae Whan 한국섬유공학회 2013 한국섬유공학회지 Vol.50 No.6
A conducting polyaniline-$Fe_3O_4$ nanohybrid was synthesized via click coupling of iron oxide nanoparticles and 2-ethynylaniline. Covalent functionalization of the azide-functionalized iron oxide nanoparticles and the 2-ethynylaniline was confirmed with Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, and the coating of polyaniline on iron oxide nanoparticles was confirmed with field-emission scanning electron microscopy. The nanohybrid incorporated into a poly(vinyl alcohol) (PVA) matrix by solution casting showed excellent compatibility with the PVA. Consequently, the mechanical properties and electrical conductivities of the resultant composite films were improved remarkably. This click coupling protocol offers the possibility of completely combining the extraordinary performance of nanohybrids with PVA properties.
지방농정 자율성 확대를 위한 농림수산 포괄보조금제 운용 방안
조재환 ( Jae Whan Cho ),이한성 ( Han Sung Lee ) 한국농촌계획학회 2013 농촌계획 Vol.19 No.3
This study proposed the introduction of the block grant in agriculture, forestry, and fishery sectors so that the local governments get greater autonomy in agricultural policy. First of all, theoretical background on block grant was reviewed and present situation in Korea regarding block grant was examined. Four criteria were set to evaluate the eligibility for the block grant. Four criteria imply that block grant is more appropriate with small-scaled similar projects, high locality projects, easily evaluated projects, and easily formula-applied projects. Applying these criteria to the projects subsidized by the national government, appropriate projects as the block grant were selected. Finally, specific operation scheme of the block grant was proposed.
탄소나노튜브-폴리우레탄 나노복합체의 역학적, 열적 및 전기적 성질
정민,조재환,Jung, Min,Cho, Jae-Whan 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.2
Nanocomposites composed of thermoplastic polyurethane block copolymer (PU) and multi-walled carbon nanotube (CNT) were prepared by melt-compounding, and their mechanical and thermal properties were investigated along with electrical conductivity. Modulus of composites increased proportionally with increasing CNT content breaking stress tended to decrease except 1% CNT, and strain-at-break decreased gradually. However, composites using sonicated nanotube showed different mechanical behavior, and especially, their strain-at-break increased largely due to better dispersion of nanotube in PU. It was considered that tensile properties of composites were dependent on CNT content, dispersion of nanotubes in matrix, and phase separation between hard and soft segments of PU due to nanotube addition. With increasing CNT content, glass transition temperature and maximum loss tangent decreased and thermal stability improved. Also electrical conductivity increased to 10$^{-4}$ S/cm for the 3% CNT composite.
Click Chemistry를 이용한 다중벽 탄소나토튜브의 키토산 기능화
류희정,조재환,김영호,Ryu, Hee-Jeong,Cho, Jae-Whan,Kim, Young-Ho 한국섬유공학회 2011 한국섬유공학회지 Vol.48 No.3
Multi-walled carbon nanotubes (MWNTs) were functionalized with chitosan using Cu-catalyzed Huisgen [3+2] cycloaddition click chemistry. Azide moiety-chitosan was prepared by synthesizing azide-moiety epichlorohydrin and its subsequent reaction with chitosan. Alkyne-functionalized MWNTs were separately prepared by the diazotization reaction of MWNTs with p-amino propargyl ether. Covalent functionalization of the MWNTs was accomplished through click coupling between the alkyne-derived MWNTs and the azide moiety-chitosan. The reaction was confirmed by FT-IR, Raman, SEM, and TEM measurements. Functionalized chitosan was observed by TEM on the surfaces of the MWNTs after click coupling. Electrical heating with a maximum of $6.8^{\circ}C$ occurred when a voltage of 60 V was applied to the MWNT/chitosan composites, further demonstrating the chitosan functionalization of the MWNTs.
탄소나노튜브와 하이퍼브랜치 폴리우레탄 혼합용액의 스프레이 코팅에 의한 직물의 전기발열 효과와 발수성
이선영,조재환,김영호,Lee, Sun-Young,Cho, Jae-Whan,Kim, Young-Ho 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.3
Cotton and polyester fabrics were coated with a hyperbranched polyurethane (HBPU) solution including multi-walled carbon nanotubes (MWNTs) using a spraying method. The MWNT-coated fabrics showed good water repelling properties at $70^{\circ}C$ and room temperature due to presence of well dispersed MWNTs on the fabric surface. The electrical heating effect of the MWNT-coated fabrics was demonstrated when a DC voltage of 10-30 V was applied to the fabrics, which was dependent on the electrical conductivity of the MWNT/HBPU composites. The MWNT coating on the fabric surface by spraying may be a good method for achieving electrical heating and water repellence.
Poly(L-lysine)로 기능화한 다중벽 탄소나노튜브의 합성과 탄소나노튜브에의 Biomineralization
소향화,조재환,So, Hyang-Hwa,Cho, Jae-Whan 한국섬유공학회 2007 한국섬유공학회지 Vol.44 No.4
Multi-walled carbon nanotubes (MWNTs) were functionalized with poly(L-lysine)(PLL) and used to prepare the silica-MWNT nanocomposites via biomineralization route in the presence of PLL by a sol-gel reaction of tetramethyl orthosilicate. The MWNT-graft-PLL (MWNT-g-PLL) could be synthesized, and it was evidenced by FT-IR spectroscopy and TEM measurement. In TEM observation, the morphology of PLL molecules covered on MWNTs was clearly shown. The formation of silica on MWNT and MWNT-PLL was carried out in two methods called as solution phase and solid phase. The presence of PLL in biomineralization affected dominantly an amount of silica formed in both solution phase and solid phase, which was evidenced in the EDS image measurements.
폴리우레탄으로 가교화한 탄소나노튜브 나노복합체의 합성과 특성
이선영,정용채,조재환,전병철,Lee, Sun-Young,Jung, Yong-Chae,Cho, Jae-Whan,Chun, Byoung-Chul 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.4
Polyurethane(PU)-crosslinked multi-walled carbon nanotubes(MWNTs) with different MWNTs content were synthesized, and their morphology and crystallization were investigated. The crosslinking of MWNTs with PU was achieved by reacting MWNTs treated chemically in the mixed acids with prepolymer obtained from a reaction of diisocyanate and polyol. The functioanlization of MWNTs with PU was confirmed by FT-IR, Raman, and XPS measurements, and their morphology was observed by SEM and TEM measurements. Optimum content of MWNTs for PU-crosslinked MWNTs was dependent on an amount of prepolymer and concentration of -OH group in MWNTs. The crystallinity of poly($\varepsilon$-caprolactone)-based PU decreased with an increase of MWNTs content, and it was ascribed to the confinement of crystallization of PCL molecules due to the crosslinking of PU with MWNTs.