• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.10.2-10.2
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• 2011

The design and synthesis of protein-like polymers is a fundamental challenge in materials science. A biomimetic approach is to explore the impact of monomer sequence on non-natural polymer structure and function. We present the aqueous self-assembly of two peptoid polymers into extremely thin two-dimensional (2D) crystalline sheets directed by periodic amphiphilicity, electrostatic recognition and aromatic interactions. Peptoids are sequence-specific, oligo-N-substituted glycine polymers designed to mimic the structure and functionality of proteins. Mixing a 1:1 ratio of two oppositely charged peptoid 36 mers of a specific sequence in aqueous solution results in the formation of giant, free-floating sheets with only 2.7 nm thickness. Direct visualization of aligned individual peptoid chains in the sheet structure was achieved using aberration-corrected transmission electron microscopy. Specific binding of a protein to ligand-functionalized sheets was also demonstrated. The synthetic flexibility and biocompatibility of peptoids provide a flexible and robust platform for integrating functionality into defined 2D nanostructures. In the later part of my talk, we describe the use of metal ions to construct two-dimensional hybrid films that have the ability to self-heal. Incubation of biomimetic peptoid polymers with specific divalent metal ions results in the spontaneous formation of uniform multilayers at the air-water interface. We anticipate that ease of synthesis and transfer of these two-dimensional materials may have many potential applications in catalysis, gas storage and sensing, optics, nanomaterial synthesis, and environmentally responsive scaffolds.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1603-1606
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• 2009

A new 1D oxalato bridged compound Ni(en)(ox)-2$H_2$O, (ox = oxalate; en = ethylenediamine) has been hydrothermally synthesized and characterized by single crystal X-ray diffraction, IR spectrum, TG analysis, and magnetic measurements. In the structure the Ni atoms are coordinated with four oxygen atoms in two oxalate ions and two nitrogen atoms in one ethylenediamine molecule. The oxalate anion acts as a bis-bidentate ligand bridging Ni atoms in cis-configuration. This completes the infinite zigzag neutral chain, [Ni(en)(ox)]. The interchain space is filled by water molecules that link the chains through a network of hydrogen bonds. Thermal variance of the magnetic susceptibility shows a broad maximum around 50 K characteristic of one-dimensional antiferromagnetic coupling. The theoretical fit of the data for T > 20 K led to the nearest neighbor spin interaction J = -43 K and g = 2.25. The rapid decrease in susceptibility below 20 K indicate this compound to be a likely Haldane gap candidate material with S = 1.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1113-1117
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• 2009

The one-dimensional coordination polymers, $[Cu^{II}(L)(NO_3)_2]_n$ (1) and {$[Cu^{II}(L)(NO_3)]{\cdot}2H_2O}_{2n} (2), were synthesized from $Cu(NO_3)_2{\cdot}3H_2O$ and 2-[(pyridin-3-ylmethyl)amino]ethanol (L, PMAE) in methanol by controlling the molar ratio of copper(II) salt. Copper(II) ion in 1 has one pyridine group of PMAE whose an aminoethanol group coordinates adjacent copper(II) ion. As the pyridine group is bonded to neighboring copper(II) ion, 1 becomes a one-dimensional chain. Contrary to 1, the structure of 2 shows that the oxygen atom of ethoxide group is bridged between two copper(II) ions, which forms a dinuclear complex. Additionally, the pyridine group of PMAE included one dinuclear unit is coordinated to the other dimeric one each other, which leads to a one-dimensional polymer. Due to the structural differences, 1 exhibits weak antiferromagnetic interaction, while 2 shows strong antiferromagnetic interaction. Due to direct spin exchange via oxygen of PMAE 2 has a much strong spin coupling than 1.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.137-140
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• 2005

Resin transfer molding (RTM) is one of the most popular processes for producing fiber reinforced polymer composites. In the manufacture of complex thick composite structures, analysis on flow front advancement on the resin impregnating the multi-layered fiber preform is helpful for the optimization of the process. In this study, three-dimensional mold filling simulation of RTM is carried out by using CVFEM (Control Volume Finite Element Method). On the assumption of isothermal flow of Newtonian fluid, Darcy’s law and continuity equation are used as governing equations. Different permeability tensors employed in each layer are obtained by experiments. Numerically predicted flow front is compared with experimental one in order to validate the numerical results. Flow simulations are conducted in the two mold geometries, rectangular plate and hollow cylinder. Permeability tensor of each layer preform in Cartesian coordinate system is transformed to cylinder coordinates system so that the flow within the multi-layered preforms of the hollow cylinder can be calculated exactly. Our emphasis is on the three dimensional flow analysis for circular three-dimensional braided preform, which shows outstanding mechanical properties such as high impact strength and toughness compared with other conventional two-dimensional laminar-structured preforms.

• Journal of Advanced Marine Engineering and Technology
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• 제34권3호
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• pp.369-375
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• 2010

The two-dimensional finite element formulation for the basic field equations governing electrochemical responses of ionic conducting polymer-metal composite(IPMC) actuators is proposed in the present study. Biaxial deformation of a platinum plated Nafion actuator having 4 electrodes is dominated by electro-osmosis of hydrated ions and self-diffusion of free water molecules. Some numerical studies for IPMC actuators with electric field are carried out in order to show the validity of the proposed formulation and electric field analysis for the initial condition of total charge distribution are conducted using commercial code ANSYS/Emag.

• 한국인쇄학회지
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• 제14권1호
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• pp.89-114
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• 1996

Liquid crystal-polymer composite(LCPC) films consisting of a continuous LC phase embedded in a three-dimensional network of polymer matrix are formed by photopolymerization-induced phase separ on. The LCPC films are switched from a light-scattering stats to a highly transparent stats on the application of electric fields. Since the alignment of LC molecular determines the electro-optical properties of films, the requirement for good contrast is to generate the nematic phase at high concentration. On the other hand, the concentration of UV-curable monomer must be increased above some critical value to from the flexible matrix of unbounded polymer. The mixing ratio of LC and UV-curable monomer affects the electro-optical and viscoelastic properties of LCPD films in two opposing ways. By controlling the phase separation process, at an LC fraction of 0.7, the maximum performance of LCPC films has been achieved, the response time of which is 2ms on the application of electric fields.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.25-26
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• 2006

Azobenzene functionalized polymers have been extensively investigated due to the potential applications in the areas of optical switching, optical elements, optical information storage, and nonlinear optics. These applications are mainly achievable due to photoinduced properties of azobenzene groups with photoisomerization and photoinduced anisotropy. We report applications to the optoelectronic devices using inscribed one-(1D) and two-dimensional (2D) SRGs on azo polymer films. The inscribed holographic SRGs patterns were useful to control or enhance optoelectronic properties such as transparent electrode patterning, hybrid solar cell and ultraviolet GaN-based LED.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.303-305
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• 1997

The advantage of application polymer instead of conventional porcelain as the housing material for arrester is that light weight, shorter section length of arrester would be possible due to the use of an insulated hanger (mold compound). also, polymer arrester has very good characteristics in design versatility as well as excellent resistance to moist ingress and pollution performance. The finite element method is widely used to calculate for electromagnetic devices. In this paper, we perform the each conditional analysis of PC with an advanced graphical user interface(GUI) using the vector fields simulator. And we try to analyze electromagnetic fields through the conventional two dimensional analysis in case of high voltage contamination on the electrode of a arrester.

• 센서학회지
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• 제30권3호
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• pp.125-130
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• 2021

In this study, the degree of alignment of polymer microfibers produced by electrospinning using a rotating water collector was evaluated. Aligned micro- and nano-fibers are required in various practical applications involving anisotropic properties. The degree of fiber alignment has many significant effects; hence, and accurate quantitative analysis of fiber alignment is necessary. Therefore, this study developed a simple and efficient method based on two-dimensional fast Fourier transform, followed by ellipse fitting. As a demonstrative example, the polymer microfibers were electrospun on the rotating water collector as the alignment of microfibers can be easily controlled. The analysis shows that the flow velocity of the liquid collector significantly affects the electrospun microfiber alignment, that is, the higher the flow velocity of the liquid collector, the greater is the degree of microfiber alignment. This method can be used for analyzing the fiber alignment in various fields such as smart sensors, fibers, composites, and textile engineering.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.355-355
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• 2006

In this study, we have applied principal component analysis-based 2D (PCA2D) correlation spectroscopy to the temperature-dependent IR spectra of biodegradable poly(hydroxyalkanoate). PCA2D analysis reveals clearly that there are two components in crystalline band of C=O stretching mode without being hampered by noise. To better understand the thermal behavior of biodegradable poly(hydroxyalkanoate), eigenvalue manipulating transformation (EMT) technique was also employed. By uniformly lowering the power of a set of eigenvalues associated with the original data, the subtle contributions from minor eigenvectors are highlighted. Details of thermal behavior of biodegradable poly(hydroxyalkanoate) studied by PCA2D correlation spectroscopy with EMT will be discussed.