• Macromolecular Research
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• 제17권5호
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• pp.301-306
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• 2009

This work has demonstrated that a novel amphiphilic poly(epichlorohydrine)-graft-polystyrene (PECH-g-PS) copolymer at 34:66 wt% was synthesized via atom transfer radical polymerization (ATRP) of styrene using PECH as a macroinitiator. The structure of the graft copolymer was characterized by nuclear magnetic resonance ($^1H$ NMR) and FTIR spectroscopy, demonstrating that the "grafting from" method using ATRP was successful. The self-assembled graft copolymer was used as a template film for the in-situ growth of silver nanoparticles from $AgCF_3SO_3$ precursor under UV irradiation. The in situ formation of silver nanoparticles with 6-8 nm in average size in the solid state template film was confirmed by transmission electron microscopy (TEM), UV-visible spectroscopy and wide angle X-ray scattering (WAXS). Differential scanning calorimetry (DSC) also displayed the selective incorporation and the in situ formation of silver nanoparticles within the hydrophilic PECH domains, probably due to stronger interaction of the silvers with the ether oxygens of PECH backbone than that with hydrophobic PS side chains.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3001-3004
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• 2014

A series of hydroxyl-derivatized quaternized polymers were successfully synthesized by atom transfer radical polymerization (ATRP) and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide and alkynes (click chemistry), followed by quaternization reactions. ATRP was employed to synthesize poly(2-hydroxyethyl methacrylate) (PHEMA), followed by introduction of alkyne groups using pentynoic acid, leading to HEMA-Alkyne. 2-Azido-1-ethanol and 3-azido-1-propanol were combined with the HEMA-Alkyne backbone via click reaction, resulting in triazole-ring containing hydroxyl-derivatized polymers. Quaternization reactions with methyl iodide were conducted on the triazole ring of each polymer. Molecular weight, molecular weight distribution, and the degree of quaternization (DQ) were determined by gel permeation chromatography (GPC) and $^1H$ NMR spectroscopy. The average molecular weight ($M_n$) of the resulting polymers ranged from $5.9{\times}10^4$ to $1.05{\times}10^5g/mol$ depending on the molecular architecture. The molecular weight distribution was low ($M_w/M_n$ = 1.26-1.38). The transmission spectra of the 0.1 wt % aqueous solutions of the resulting quaternized polymers at 650 nm were measured as a function of temperature. Results showed that the upper critical solution temperature (UCST) could be finely controlled by the level of DQ.

• 멤브레인
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• 제21권2호
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• pp.193-200
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• 2011

원자전달 라디칼 중합(ATRP)에 의해 poly(vinyl chloride) (PVC) 주사슬과 poly(styrene sulfonic acid) (PSSA) 곁사슬로 되어있는 양쪽성 PVC-g-PSSA 가지형 공중합체를 합성하였다. PVC-g-PSSA 가지형 공중합체 고분자를 템플레이트로 사용하고 졸겔법을 적용하여, 결정성 아타네제상의 미세기공 이산화티타튬 필름을 제조하였다. $TiO_2$ 전구체인 TTIP를 친수성인 PSSA 영역과 선택적으로 작용시켜 $TiO_2$ 메조기공 필름을 성장하였으며, 이를 주사전자 현미경 (SEM)과 엑스레이회절 (XRD)분석을 통해 분석하였다. 스핀코팅 횟수와 P25 도입에 따른 염료감응 태양전지 성능을 체계적으로 분석하였다. 그 결과 준고체 고분자 전해질을 이용하였을 때, 100 mW/$cm^2$ 조건에서 에너지 변환 효율이 2.7%에 이르렀다.

• 멤브레인
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• 제20권1호
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• pp.55-61
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• 2010

원자전달 라디칼 중합을 이용하여 polystyrene-b-poly(oxyethylene methacrylate) (PS-b-POEM) 블록 공중합체를 합성하고, FT-IR을 통해 중합이 성공적으로 이루어졌음을 확인하였다. 또한 자기 조립된 블록 공중합체 막을 제조한 후, 전구체 $AgCF_3SO_3$ 도입과 UV 조사를 통해 고체상에서 은 나노입자를 성장시켰다. TEM 전자현미경과 UV-visible 분광학 분석을 통해 블록 공중합체 막의 내부에 은 나노입자가 형성된 것을 확인하였고, 또한 친수성 POEM 영역의 함량을 조절함으로써 나노입자의 크기를 조절할 수 있었다. 금속 나노입자를 제조하는 데 있어서 POEM 함량이 적은 블록 공중합체가 더 효과적임을 확인하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2005년도 추계학술대회 논문집
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• pp.89-92
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• 2005

A microcapsule for drug delivery was successfully produced by utilizing the flow-through droplet-based supramolecular self-assembly in a crossed microchannel network. The PS-b-PMMA block copolymer synthesized atom transfer radical polymerization (ATRP) was initially formed as microdroplets and after the evaporation process it turned to spherical capsule by polymer self-assembly of the micro domains. The characteristics were studied using various analysis methods.

• 멤브레인
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• 제19권2호
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• pp.96-103
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• 2009

본 연구에서는 poly(vinyl chloride) (PVC)가지형 공중합체 전해질과 헤테로폴리산(HPA)을 이용하여 유무기 합성 전해질막을 제조하였다. poly(vinyl chloride)-g-poly(styrene sulfonic acid) (PVC-g-PSSA)는 PVC의 이차 염소의 직접적인 개시를 이용한 atom transfer radical polymerization (ATRP)로 합성하였다. 이때, HPA 나노입자는 수소 결합을 통해 PVC-g-PSSA 가지형 공중합체와 결합하는 것을 FT-IR spectroscopy를 통하여 확인하였다. 전해질막의 수소이온 전도도는 HPA의 질량 분율이 0.3이 될 때까지 상온에서 0.049에서 0.068 S/cm로 증가하였다. 이것은 HPA 나노입자 고유의 전도도와 가지형 공중합체가 가지고 있는 술폰산의 강화된 산도 때문이라고 추정된다. 합습률은 HPA의 질량 분율이 0.45까지 증가할수록 130에서 84%로 감소하였다. 이것은 HPA나노입자와 고분자 메트릭스 사이의 수소 결합의 상호작용 때문에 물을 흡수하는 site의 수가 감소한 결과라고 볼 수 있다. 열중량 분석결과 HPA의 농도가 증가할수록 전해질막의 열적 안정성이 강화된다는 것을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1521-1525
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• 2009

Thermosensitive block copolymers of ethylene oxide and N-isopropylacrylamide (NIPAM) were synthesized. A five armed star shape oligo(ethylene oxide) initiator with a cyclotriphosphazene core was prepared and used for the atom transfer radical polymerization (ATRP) of NIPAM. The lower critical solution temperatures (LCSTs) of the copolymers were 36 to 46 ${^{\circ}C}$, higher than that of PNIPAM (32 ${^{\circ}C}$), depending on their molecular weights. The copolymers were soluble in water below the LCSTs but formed micelles above the LCSTs. The thermosensitive micellization behaviors of the polymers were investigated by fluorescence spectroscopy. With increasing the temperature of an aqueous solution of P2 and pyrene above the LCST, the peak of 333 nm red-shifted to appear around 339 nm and its intensity increased significantly, indicating the micelle formation. The transfer of pyrene into the micelles was also confirmed by a confocal laser scanning microscope. The fluorescence image obtained from P2 in an aqueous pyrene solution exhibited a green emission resulting from the pyrene transferred into the micelles. Salt effects on the solubility of the copolymers in an aqueous solution were investigated. The LCST of P2 decreased sharply as the concentration of sodium chloride increased, while decreased slowly with potassium chloride.

• 전기화학회지
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• 제14권2호
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• pp.83-91
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• 2011

Mesoporous titanium dioxide ($TiO_2$) thin films were prepared using poly(vinyl chloride)-graft-poly(N-vinyl pyrrolidone) (PVC-g-PVP) as a templating agent via sol-gel process. Grafting of PVC chains from PVC backbone was done by atom transfer radical polymerization (ATRP) technique. The successful grafting of PVP to synthesize PVC-g-PVP was checked by fourier-transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). The carbonyl group interaction of PVC-g-PVP graft copolymer with $TiO_2$ was confirmed by FT-IR. The porous morphologies of the $TiO_2$ films genereated after calcination at $450^{\circ}C$ was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mesoporous $TiO_2$ films with 580 nm in thickness were used as a photoelectrode for solid state dye sensitized solar cell (DSSC) and showed an energy conversion efficiency of 1.05% at 100 $mW/cm^2$.

• Korean Membrane Journal
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• 제10권1호
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• pp.20-25
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• 2008

Proton conducting composite membranes were prepared by solution blending of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-graft-poly(sulfopropyl methacrylate) (P(VDF-CTFE)-g-PSPMA) graft copolymer and heteropolyacid (HPA). The P(VDF-CTFE)-g-PSPMA graft copolymer was synthesized by atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of P(VDF-CTFE). FT-IR spectroscopy revealed that HPA nanoparticles were incorporated into the graft copolymer via hydrogen bonding interactions. The water uptake of membranes continuously decreased with increasing HP A concentration up to 45wt%, after which it slightly increased. It is presumably due to the decrease in number of water absorption sites due to hydrogen bonding interaction between the HP A particles and the polymer matrix. The proton conductivity of membranes increased with increasing HPA concentration up to 45wt%, resulting from both the intrinsic conductivity of HP A particles and the enhanced acidity of the sulfonic acid of the graft copolymer.

• Korean Membrane Journal
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• 제11권1호
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• pp.1-7
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• 2009

This work reports the preparation of proton conductive crosslinked polymer electrolyte membranes by blending poly(vinyl chloride)-g-poly(hydroxyl ethyl acrylate) (PVC-g-PHEA) and poly(vinyl alcohol) (PVA). The PHEA chains of the graft copolymer were crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of polymer matrix and -COOH of SA. The PVC-g-PHEA graft copolymer was synthesized via atom transfer radical polymerization (ATRP) using direct initiation of the secondary chlorines of PVC backbones. Ion exchange capacity (IEC) continuously increased with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. However, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane exhibited a maximum proton conductivity of 0.026 S/cm at 20.0 wt% of SA concentration, which is presumably due to competitive effect between the increase of ionic sites and the crosslinking reaction.