• Applied Microscopy
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• 제26권3호
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• pp.379-388
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• 1996

Structure of premartensite in $Ti_{50}Ni_{49}Fe_1\;and\;Ti_{50}Ni_{50}$ prepared by self-propagating high temperature synthesis (SHS) method has been investigated by a detailed transmission electron microscopy. $Ti_{50}Ni_{49}Fe_1$ consists of microdomain area and needle type domain area. On the other hand, $Ti_{50}Ni_{50}$ consists of microdomain-free and microdomain area, and needle type domain area. Various types of extra superreflections, such as 1/2<100>, 1/2<110> and 1/4<210> type superreflection have been observed in the selected area electron diffractions from microdomain area. Such extra superreflections are due to transformation from B2 structure to distorted B2 structure or premartensite. The present study shows that incommensurate phase forms as an intermediate phase during martensitic transformation. Particularly, in Fe-free $Ti_{50}Ni_{50}$, two types of matrix phases have been observed, microdomain and microdomain-free area. Types of extra superreflections in $Ti_{50}Ni_{50}$ are different from those in $Ti_{50}Ni_{49}Fe_1$, i.e. 1/7<321> type superreflections have been observed, instead of 1/2<110>, 1/2<100>, 1/4<210> types in $Ti_{50}Ni_{49}Fe_1$.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2689-2693
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• 2014

The control over microstructure in block copolymer thin films using external electric fields has become an interesting research topic. In this article, the effect of nanoparticle on the microdomain alignments in block copolymer (polystyrene-b-poly(2-vinylpyridine)/nanoparticle (Au) thin films under electric fields has been examined with transmission electron microscopy. The homogeneous dispersion of Au nanoparticles into the block copolymer matrix was achieved by surface modification of nanoparticles with compatible ligands. Compared with the phenomenon seen in the pristine block copolymer thin films, a peculiar alignment behavior was observed in the block copolymer/nanoparticle hybrid thin films under electric fields. In addition, the different pathways observed in the pristine and nanoparticle incorporated block copolymer thin films were also monitored as a function of exposure time. This work can provide the fundamental information for understanding microdomain alignment in block copolymer/nanoparticle thin films under external electric fields.

• 유변학
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• 제7권2호
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• pp.75-100
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• 1995

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.71-72
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• 2006

We investigated a simultaneous living anionic polymerization process of isoprene (I) and 4styrene-d_8$ (S) in $benzene-d_6$ as a solvent with sec-buthyllithium as an initiator into polyisoprene(PI)-block-poly($styrene-d_8$)(PS) and the polymerization-induced molecular self-assembling process. This process was observed in-situ by time-resolved small-angle neutron scattering (SANS) experiment. The SANS profiles measured exhibited three time regions, where (i) the selective growth of PI chains occurs; (ii) the living chain ends switch from isoprenyllithium to styryllithium, and (iii) the SANS exhibited the polymerization induced disorder-to-order transition and order-to-order transition.

• 생명과학회지
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• 제32권2호
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• pp.148-154
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• 2022

국소접착인산화효소(FAK)는 국소접착부에서 세포부착, 세포이동, 세포역학적 신호전달 등에 관여한다고 알려져 있다. 그러나 세포 외 기질(ECM)과 상호작용하는 인테그린 막단백질과 함께 위치하는 세포막 미세영역(membrane microdomain)의 종류와 ECM 구성에 따른 FAK 활성은 여전히 불분명하다. 형광 공명 에너지 전달(FRET)을 기반으로 유전적으로 인코딩 된 바이오센서는 세포 내 FAK 신호를 높은 시공간 해상도로 제공할 수 있다. 본 연구에서는 유리, 제1형 콜라겐, 피브로넥틴, 라미닌의 ECM 조건에서 FRET 기반 막 표적 FAK 바이오센서를 사용하여 지질유동섬(Lipid raft) 및 비-지질유동섬(non-Lipid raft)에서 FAK의 활성을 분석하고 시각화 하였다. 흥미롭게도, 지질유동섬에서 라미닌 조건 하의 FAK 활성은 다른 ECM 조건보다 낮았고, 비-지질유동섬에서 FAK 활성은 다른 ECM 조건보다 낮았다. 동일한 ECM 조건 상의 비교에서는 피브로넥틴 조건일 때 지질유동섬에서 비-지질유동섬 보다 높은 FAK 활성이 관측되었다. 따라서 이번 연구는 FAK 활성도가 ECM 유형 및 세포막 미세영역에 따라 특이적으로 조절되는 것을 시각적, 정량적으로 보여준다.

• Macromolecular Research
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• 제17권10호
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• pp.757-762
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• 2009

The micro domain structures and crystallization behavior of the binary blends of poly(methyl methacrylate)-b-poly(pentafluorostyrene)-b-poly(methyl methacrylate) (PMMA-PPFS-PMMA) triblock copolymer with a low molecular weight poly(vinylidene fluoride) (PVDF) were investigated by small-angle X-ray scattering (SAXS), small-angle light scattering (SALS), transmission electron microscopy (TEM), optical microscopy, and differential scanning calorimetry (DSC). A symmetric, PMMA-PPFS-PMMA triblock copolymer with a PPFS weight fraction of 33% was blended with PVDF in N,N-dimethylacetamide (DMAc). In the wide range of PVDF concentration between 10.0 and 30.0 wt%, PVDF was completely incorporated within the PMMA micro domains of PMMA-PPFS-PMMA without further phase separation on a micrometer scale. The addition of PVDF altered the phase morphology of PMMA-PPFS-PMMA from well-defined lamellar to disordered. The crystallization of PVDF significantly disturbed the domain structure of PMMA-PPFS-PMMA in the blends, resulting in a poorly-ordered morphology. PVDF displayed unique crystallization behavior as a result of the space constraints imposed by the domain structure of PMMA-PPFS-PMMA. The pre-existing microdomain structures restricted the lamellar orientation and favored a random arrangement of lamellar crystallites.

• 폴리머
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• 제28권6호
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• pp.509-518
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• 2004

비대칭 블록 공중합체와 단일고분자로 구성된 블렌드의 미세 도메인 구조와 결정화 거동을 소각 X-선 산란, 광학 현미경 및 DSC를 사용하여 조사하였다. 본 연구에서는 폴리(메틸 메타크릴레이트) 블록의 무게 분률이 0.53인 폴리(메틸 메타크릴레이트)-폴리스티렌 이종 블록 공중합체 (PMMA-b-PS)를 저분자량 폴리(비닐리덴 플루오라이드) (PVDF)와 혼합하였다. PVDF 함량 증가에 따라 블렌드 미세구조가 라멜라에서 실린더 구조로 전이하였으며, PVDF의 결정화는 결정화 이전에 형성된 미세구조의 배열을 교란시켜 질서도가 낮은 형태를 야기시켰다. 또한, PVDF 결정화 거동은 PMMA 블록과의 혼화성 및 미세 도메인에 의해 부가되는 공간적 제한에 큰 영향을 받았다.

• 대한의용생체공학회:의공학회지
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• 제8권2호
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• pp.199-204
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• 1987

ABA type block copolymers composed of r benzyle L-glutamate as the A component and poly(ethylene glycol) as the B components were obtained. Platelet adhesion on their sunfaces was investigated by a column elusion method to examine the effects of microdomain and secondary structure. The number of platelets adhered from whole blood and plasma rich platelet was smaller for the block copolymer systems than for the homopolymers. In the block copolymer system, the number of platelets adrered on their surfaces increased with increasing the content of PEG, that is, with decreasing of a-helix of block copolymers. A thick thrombus formation on the PBLG homopolymer was observed than block copolymer by scanning electron micrographs. The platelets adhesion increased with increasing the critical surface tension of the block copolymer.

• Bulletin of the Korean Chemical Society
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• 제20권6호
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• pp.683-688
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• 1999

In deuterium NMR spectra of phosphatidylethanolamine bilayers with an extremely high content of saturated fatty acids, each C1 deuteron of the glycerol backbone gave rise to a doublet. This suggests the presence of two backbone conformations, the exchange between which is slow on an NMR time scale. The origin of the two conformations has been investigated in this work using saturated 1,2-diacyl-sn-glycero-3-phosphoethanolamine specifically deuterated in the glycerol backbone. The results showed that the two conformations originate from different domains, which have different fatty acid compositions. The differential scanning calorimetry of the bilayers suggested that the size of the domain is not large enough to show an independent phase transition. Thus, the formation of microdomains in the phosphatidylethanolamine bilayers has been concluded. Conformational difference in different domains was shown to be restricted to the C1 position of the glycerol backbone. The microdomains of phosphatidylethanolamine were retained even in the presence of other phospholipids.

• 공업화학
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• 제10권1호
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• pp.35-40
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• 1999

Hard segment 함량이 35%와 53%로 서로 다른 두 개의 열가소성 폴리우레탄 시료 (각각 TPU-35와 TPU-35)와 이들을 70/30, 50/50, 30/70 wt%로 용융 블렌딩한 조성들이 annealing 온도와 시간에 따라 변화할 수 있는 유리전이온도와 용융피이크, 분자량 및 분자량 분포도의 변화를 관찰하였다. TPU의 $T_g$는 hard segment 함량이 많을수록 높은 값을 보였으며 annealing 온도와 시간에 따라 hard microdomain 구조의 미약한 관계에 의한 용융피이크의 크기와 온도 등이 변하였다. 이는 annealing에 의한 열이 long-range 혹은 short-range segmental motion의 거동, 비결정 microphase 구조의 order-disorder 전이, domain의 크기 및 결정구조의 질서도 등 여러 가지 복합적인 영향을 끼친 결과로 사료된다. 미세 결정의 용융 결과로 나타나는 $T_3$단일 피이크만이 존재하는 annealing 온도는 TPU-35, TPU-44와 TPU-53에 대해 각각 130, 170 및 $180^{\circ}C$이었다. Annealing 온도와 시간에 따른 분자량 및 분자량 분포도 변화 측정에서 TPU-35는 $135^{\circ}C$에서, TPU-44(TPU-35/TPU-53=50/50 블랜드)는 $170^{\circ}C$, 그리고 TPU-53은 $180^{\circ}C$에서 수평균 및 중량평균 분자량의 증가와 더불어 polydispersity(PI)는 감소를 보였다. 이 변화는 같은 조건의 annealing 온도에 따른 용융피이크 변화에서 $T_3$단일 피이크만 남게 되는 annealing온도와 일관성을 보이고 있는데, 이는 이들 시료가 특정한 annealing 온도에서 chain dissociation과 recombination이 동시에 일어나므로써 빚어진 결과로 추측된다.