• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• 폴리머
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• 제34권2호
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• pp.159-165
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• 2010

리빙 음이온 중합에 의해 sec-BuLi으로 개시된 polystyryllithium (PSLi)과 polybutadienyllithium (PBDLi)의 연쇄 말단에 di(2-pyridyl)ketone(DPK)을 반응시켜 dipyridine이 말단 관능화된 폴리스티렌과 폴리부타디엔을 각각 합성하였다. 분자량이 1000~2000 g/mol인 PSLi과 PBDLi을 사용하여 TMEDA 존재하에서 말단 DPK-관능화 반응 후 GPC에 의한 분자량 특성분석과 $^1H$-NMR, $^{13}C$-NMR 분석에 의한 고분자 말단 구조 분석을 통하여 말단 관능화 수율과 함께 유기리튬의 피리딘 링 친핵성 부가 반응으로 인한 커플링 현상을 확인하였다. PBDLi에 DPK를 부가하는 일반적인 말단 관능화 방법에 비하여 역으로 부가하는 방법에서 최대 9% 정도의 커플링 정도와 86% 이상의 관능화 수율을 보였다. 이 반응에서 LiCl 첨가효과는 없었으며, 반응온도가 낮을수록 높은 관능화 수율을 나타내었다.

• Macromolecular Research
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• 제14권3호
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• pp.272-286
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• 2006

Dendritic hyperbranched poly(methyl methacrylate)s (PMMA)s, whose branched architectures resemble the 'dendron' part(s) of dendrimer, were synthesized by an iterative methodology consisting of two reactions in each iteration process: (a) a coupling reaction of u-functionalized, living, anionic PMMA having two tert-butyldimethylsilyloxymethylphenyl(SMP) groups with benzyl bromide(BnBr)-chain-end-functionalized PMMA, and (b) a transformation reaction of the introduced SMP groups into BnBr functionalities. These two reactions, (a) and (b), were repeated three times to afford a series of dendron-like, hyperbranched (PMMA)s up to third generation. Three dendron-like, hyperbranched (PMMA)s different in branched architecture were also synthesized by the same iterative methodology using a low molecular weight, functionalized 1,1-diphenylalkyl anion prepared from sec-BuLi and 1,1-bis(3-tert-butyldime-thylsilyloxymethylphenyl)ethylene in the reaction step (b) in each iterative process. Furthermore, structurally similar, dendron-like, hyperbranched block copolymers could be successfully synthesized by the iterative methodology using $\alpha$-functionalized, living, anionic poly(2-(perfluorobutyl) ethyl methacrylate) (PRfMA) in addition to $\alpha$-functionalized, living PMMA. Accordingly, the resulting block copolymers were comprised of both PMMA and PRfMA segments with different sequential orders. After the block copolymers were cast into films and annealed, their surface structures were characterized by angle-dependent XPS and contact angle measurements. All three samples showed significant segregation and enrichment of PRfMA segments at the surfaces.

• Macromolecular Research
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• 제17권10호
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• pp.770-775
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• 2009

$\omega$-Anhydride-functionalized poly(ethylene oxide) (PEO) obtained from chain-end functionalization and anionic ring-opening polymerization of ethylene oxide using n-butyllithium with potassium t-butoxide in the presence of dimethylsulfoxide (DMSO) was found to be an efficient material for the preparation of water-soluble, polymeric pro-drugs. The reaction of $\omega$-anhydride-functionalized PEO with sulfonamide or with vancomycin provided an efficient method to produce corresponding, water-soluble, PEO-conjugated sulfonamide or PEO-conjugated, vancomycin pro-drugs. These were used successfully to prepare water-dispersible, silver nanoparticles. In this study, the particle sizes were in the range of $5{\sim}40$ nm. The resulting products were characterized by $^1H$ NMR spectroscopy, transmission electron microscopy, electron and X-ray diffraction, size exclusion chromatography, and UV/Visible spectroscopy.

• Macromolecular Research
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• 제8권1호
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• pp.44-52
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• 2000

Styrenic macromonomers with/without a silyloxy-functional group were synthesizedvia chain-end functionalization using 4-vinylbenzyl chloride as a terminating agent insec-butyllithium-initiated polymerization of styrene. The yields were 92 mol% for the silyloxy group and 88 mol% for the styrenic unit. Crystalline polystyrene-g-amorphous polystyrenes were synthesized by (η$^{5}$ -indenyl)-trichlorotitanium ((Ind)TiCl$_3$)-catalyzed copolymerizations of the macromonomers with styrene in the presence of methyl-aluminoxane (MAO) in toluene at 4$0^{\circ}C$. The macromonomer having $\alpha$, $\alpha$'-bis (4-[tert-butyldimethylsilyl-oxy]phenyl) group was also utilized for the preparation of a precursor of hydroxyl-functionalized syndio-tactic polystyrene. The obtained polymers were characterized by a combination of$^1$H, $^{13}$ C NMR spectroscopic, size exclusion chromatographic, and differential scanning calorimetric analysis. The (Ind)TiCl$_3$-catalyzed copolymerization of styrene with the macromonomer carrying the silyloxy functional group was found to be an efficient method to modify syndiotactic polystyrene without a great loss of physica] property by controlling the feud ratio of the macromonomer.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.1-2
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• 2003

While aromatic polyimides and polyamides have found widespread use as high performance polymers, the present work addressed the need for organosoluble materials through the use of a hyperbranching scheme. The $AB_2$ monomers were prepared. The $AB_2$ monomers were then polymerized via aromatic fluoride-displacement and Yamazaki reactions to afford the corresponding hydroxyl-terminated hyperbranched polyimides (HT-PAEKI) and amine-terminated hyperbranched polyamides, respectively. HT-FAEKI was then functionalized with allyl and propargyl bromides as well as epichlorohydrin to afford allyl-terminated AT-PAEKI, propargyl-terminated PT-PAEKI, and epoxy (glycidyl)-terminated ET-PAEKI, in that order. All hyperbranched poly(ether-ketone-imide)s were soluble in common organic solvents. AT-PAEKI was blended with a bisphenol-A-based bismaleimide (BFA-BMI) in various weight ratios. Thermal, rheological, and mechanical properties of these blend systems were evaluated. Two characteristic hyperbranched polyamides, which the one has para-electron donating groups to the surface amine groups and the other has para-electron withdrawing groups to the surface amine groups, were selected to compare BMI curing behaviors. The electron rich polymer displayed ordinary Michael addition type exothermic reaction, while electron deficient polymer did display unusual curing behaviors. Based on analytical data, the later system provided the strong evidences to support room temperature curing of BMI by reactive intermediates instead of reactive primary amine groups on the macromolecule surface.