• 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.

• Macromolecular Research
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• 제16권8호
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• pp.686-694
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• 2008

We studied the molecular shapes and structural characteristics of a 33-armed, star polystyrene (PS-33A) and two $3^{rd}$-generation, dendrimer-like, star-branched poly(methyl methacrylate)s with different architectures (pMMA-G3a and PMMA-3Gb) and 32 end-branches under good solvent and theta ($\Theta$) solvent conditions by using synchrotron small angle X-ray scattering (SAXS). The SAXS analyses were used to determine the structural details of the star PS and dendrimer-like, star-branched PMMA polymers. PS-33A had a fuzzy-spherical shape, whereas PMMA-G3a and PMMA-G3b had fuzzy-ellipsoidal shapes of similar size, despite their different chemical architectures. The star PS polymer's arms were more extended than those of linear polystyrene. Furthermore, the branches of the dendrimer-like, star-branched polymers were more extended than those of the star PS polymer, despite having almost the same number of branches as PS-33A. The differences between the internal chain structures of these materials was attributed to their different chemical architectures.

• 폴리머
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• 제25권6호
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• pp.848-854
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• 2001

무정형 고분자인 ethylene-methyl acrlate-glycidyl methacrylate 공중합체 (E-MeA-GMA)와 결정성 고분자인 poly(ethylene terephthalate) (PET)와의 블렌드에서 그라프트 반응에 따른 PET의 결정화 거동을 조사하였다. PET와 E-MeA-GMA간의 그라프트 반응 수준을 torque-rheometer, FT-IR, SEM을 이용하여 확인하였으며, 반응시간에 따른 결정화 거동 변화를 DSC와 광산란 방법을 이용하여 관찰하였다. 또한 라멜라 수준의 결정구조를 소각 X선 산란법을 이용하여 조사하였다.

• 한국태양에너지학회 논문집
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• 제34권4호
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• pp.9-16
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• 2014

A proton exchange membrane is a core component in the proton exchange membrane fuel cell because the role of proton exchange membrane(PEM)is supplying proton conductivity to fuel cell, a gas separator, and insulating between an anode and cathode. Among various role of PEM, supplying proton conductivity is the most important and the proton conductivity is strongly related the structural evolution of PEM by hydration. Thus a lot of studies have done by past few decade based on small angle X-ray scattering and wide angle X-ray scattering for understanding morphological structure of the PEM. Resulting from these studies, several morphological models of hydrated PEM are proposed. Current sensing atomic force microscopy (CSAFM) can map morphology and conductance on the membrane simultaneously. It can be the best tool for studying heterogenous structured materials such as PEM. In this study, the hydration of the membrane is examined by using CSAFM. Conductance and morphological images are simultaneously mapped under different relative humidity. The conductance images, which are mapped from different relative humidity, are analyzed by statistical methode for understanding ionic channel variation in PEM.

• Macromolecular Research
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• 제14권3호
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• pp.365-372
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• 2006

Poly[styrene-b-(ethylene-co-butylene)-b-styrene](SEBS) triblock copolymer was studied by dissolving the ethylene butylene midblock in selective hydrocarbon oils. These oils differ in their aromatic, paraffinic and naphthenic content. Dynamic rheological studies showed that the storage modulus (G') exceeded the loss modulus (G') for all the gels over the entire range of frequency, thereby confirming them as physical gels. However, the behavior of G' and G' as a function of frequency depended primarily on the oil type. The gelation melting temperature decreased drastically with increased oil aromaticity. Small angle X-ray scattering studies revealed that the maximum interdomain interference shifted to a higher angle depending on the composition and type of hydrocarbon oil.

• 한국진공학회지
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• 제14권3호
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• pp.138-142
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• 2005

액상 x-선 소각산란법을 이용하여 단백질의 구조를 분석하였다. 사용한 단백질은 구조가 이미 알려진 Lysozyme과 $Bcl-XL(\vartriangle TM/\vartriangle loop)$ 그리고 $Bcl-XL(\vartriangle TM/\vartriangle loop))$에 자유롭게 움직이는 고리를 가진 $Bcl-XL(\vartriangleTM))$이다. Lysozyme와 $Bcl-XL(\vartriangle TM/\vartriangle loop)$에 대한 소각산란결과는 단백질 결정학으로부터 알려진 분자구조에서 얻은 이론적인 결과와 농도에 의한 차이정도를 제외하고는 잘 일치하였다. $Bcl-XL(\vartriangleTM))$의 경우는 단백질 결정산란 신호에서 볼 때 $Bcl-XL(\vartriangle TM/\vartriangle loop)$와 차이가 없는 것으로 알려져 있으나, 소각산란에서는 뚜렷한 차이를 나타내는 결과를 얻어 loop와 같이 쉽게 움직이는 부분을 가진 단백질을 연구하는 경우 소각산란의 장점을 확인할 수 있었다. 위 실험을 통하여 포항 가속기 연구소 4C1 빔라인의 성능은 적어도 해상도 $\sim2.2\;nm$까지 용액상의 단백질 구조를 분석할 수 있다는 것을 확인하였다.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.319-329
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• 2003

Ursolic acid (UA) and oleanolic acid (OA) are pentacyclic triterpenoids which are widely distributed in plants, and their derivatives are aglycones of many naturally occurring saponins. It is known that pentacyclic acids may possibly enhance the mechanical barrier functions of cell membranes in plants. Recently, it has been reported that OA and UA have interesting biological activities on skin, such as anti-inflammatory and anti-wrinkle activities. Since triterpenoids are extremely insoluble and their solubility problem limits skin-care application, OA and UA were encapsulated in liposomes via micelle-to-vesicle transition to overcome poorly soluble property and enhance biological efficacy. Optimal molar ratio of OA to lecithin was found to exist for producing liposomes of small hydrodynamic size and liposomal suspensions without recrystallized precipitation of OA. From electron micrograph and dynamic light scattering studies, reconstituted OA-containing liposomes without severe mechanical treatment showed small hydrodynamic size about 150 nm. Wide-angle X-ray diffraction coupled with dynamic light scattering revealed that optimal amount of OA in liposome was 25.4 mole %. In biological evaluation, OA-containing liposome significantly increased filaggrin and transglutaminase as markers of keratinocyte differentiation in epidermal layer of hairless mouse, whereas ursolic acid-containing liposome did not show noticeable increase of filaggrin and transglutaminase compared to empty liposome. It is concluded that nano-scaled liposomes containing triterpenoids were spontaneously prepared by vesicular transition from mixed micelle and liposomal triterpenoids can enhance skin absorption of triterpenoid and biological efficacy.

• 대한화장품학회지
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• 제45권1호
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• pp.1-7
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• 2019

본 연구는 세테아릴 알코올, 세틸 팔미테이트, 소르비탄 팔미테이트, 소르비탄 올리베이트, 세라마이드 등을 이용하여 제조한 액정에멀젼의 다층구조에 따른 강화된 계면막에 의해 제형의 안정성이 확보됨을 확인하였다. 편광 현미경을 통해 제형 내 몰타 크로스(maltese cross) 무늬를 확인하고, cryo-SEM을 이용하여 다층구조가 형성되었음을 확인하였다. 소각 X선 산란법(SAXS)을 이용하여 라멜라 구조 생성여부를 확인하였으며, 점도계를 이용하여 점도변화를 확인하고 정적 광 산란법(SLS)을 이용하여 입도 분포를 확인하여 액정에멀젼의 제형 안정성을 입증하였다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.348-348
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• 2006

In the present study, porcine pepsin in various pH conditions was investigated by small-angle X-ray scattering (SAXS) in order to detailed information on the structure and its variations with pH conditions. These analyses identified the structure of pepsin, and compared with that obtained by single crystallography. Moreover, this study found the structure' variations with changing pH conditions. All the results will be discussed with considering the conformational characteristics of pepsin in solution and further correlate to the biological and spectroscopic characteristics reported previously.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.35-35
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• 2011

The design and preparation of novel dye rotaxanes have gained much interest recently, since such structure usually exhibits peculiar spectral and optical changes. In spite of the promising results to date, increasing pressure remains to develop novel supramolecular structures based on stimuli-responsive systems. This presentation covers the study of inclusion complexes of cyclodextrins and various chromophores, with an emphasis on our most recent outcome of anisotropic hydrogel. In this system, physical gelation prepared from simple mixture of CD and a azo dye is completed through specific host-guest interaction. The obtained hydrogel exhibits respective morphological transitions based on supramolecular assembly and dissociation, leading to either precipitation or a sol-to-gel transition. It can identify different classes of metal ions, and, among them, naked-eye differentiation of lead ion is possible due to the coordination-induced unthreading of dye molecules. Accompanying structural changes were verified by numerous characterization techniques, including 2D-ROESY, HR-MAS, UV-Visible absorption, small-angle X-ray scattering, and induced circular dichroism measurements. Such properties discussed here will find useful in analytical applications, such as metal ion sensing and removal applications.