• Polymer(Korea)
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• v.25 no.5
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• pp.671-678
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• 2001

Sodium and zinc salts of poly(ethyaene-co-methacrylic acid) ionomers consist of three phases, i.e. ionic aggregates, amorphous, and crystalline phases. Dye molecules after soaked from the methanol solution are located near the amorphous phase or ionic aggregates within ionomer films. Depending on the location of the molecules in the ionomer film, they are under influence of dispersion forces (ethylene parts), polar forces (acid parts). and ionic dipole (ionic aggregates) interactions. The UV/Vis absorption peak of Nile Red under the dispersion force is found at near 500 nm, for the dye under the polar force effect 525 nm, and 550 and 610 nm for the dyes under $Na^+$ and $Zn^{2+}$ ionization effects, respectively. Since the divalent $Zn^{2+}$ ion has larger ionic dipole than the monovalent $Na^+$ ion, the larger red-shift of the absorption band due to the ionic dipole interaction is observed for $Zn^{2+}$ counter ion.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.335-335
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• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.

• Bulletin of the Korean Chemical Society
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• v.19 no.7
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• pp.738-742
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• 1998

A new polyamide was prepared from 4,4'-(hexafluoroisopropylidene)di-aniline and 4-[NN-bis(2-carboxyethyl)] amino-4'-nitrostilbene. This polymer was cast into thin films by spin coating cyclohexanone solution. After being poled, the electro-optic coefficients of electrode poled polymer films were measured by the reflection measurement technique using an incident laser beam of 1.3 Jim. The film poled at the field strength of 1.2 V/μm exhibited the electro-optic coefficient (r33) of 5.9 pm/V. The relaxation behavior of the poled polymer film was compared with other reported polymers bearing the same NLO chromophores. Due to stiff and highly polar nature of the backbone and also due to formation of interchain hydrogen bonds, this polymer reveals a slower relaxation characteristics. The polymer is amorphous and soluble in various organic solvents.

• Polymer Science and Technology
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• v.15 no.3
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• pp.296-302
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• 2004

최근 분자들의 자기조립 현상을 나노-바이오 소자 개발에 응용하는 연구가 활발히 진행되고 있으며, 이러한 응용을 위한 대표적인 자기조립체로는 양친성 계면활성제, 블록공증합체, 콜로이드와 초분자체를 들 수 있다. 대부분의 콜로이드가 구형 모양으로 vander Waals interaction에 의하여 3-D결정 (crystal) 형태의 자기조립구조를 형성하는 반면에, 콜로이드를 제외한 대부분의 자기조립체는 적정 조건에서 액정 (liquid crystals), 결정 (crystal) 및 무정형 (amorphous)을 형성한다. 적용하고자 하는 응용의 범위와 재료의 특성에 따라서 각 상태 (phase)를 이용할 수 있으나, 액정상을 이용하는 것과 결정상을 이용하는 경우가 대부분이다. (중략)

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.321-321
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• 2006

Aromatic diacetylenes form stable oligomeric diradicals when irradiated with UV light or heated at temperatures above their melting points. In this paper, the formation of stable diradicals is discussed, and the mechanism of polymerization in the presence of peroxide in solution, is discussed. The diphenyldiacetylene undergoes polymerization through coupling of diradicals, and not by the successive addition of radical species.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.697-699
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• 2005

The need for low cost flexible TFT display backplanes has focused attention on new processing techniques and materials. We have developed backplane technology based entirely on jet-printing, using a combination of additive and subtractive processing, and have applied this technique to both amorphous silicon and polymer TFT arrays.

• Elastomers and Composites
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• v.54 no.4
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• pp.313-320
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• 2019

A typical wear pattern was reported to resemble the fatigue crack growth behavior considering its mechanism, especially for amorphous rubbers such as styrene-butadiene rubber (SBR). In this study, the wear and crack growth rates were correlated using two separate experiments for carbon black and silica-reinforced selected rubber compounds. The wear rate was determined using a blade-type abrasion tester, where the frictional energy input during wearing was measured. The crack propagation rate was determined under different tearing energy inputs using a home-made fatigue tester, with a pure-shear test specimen containing pre-cracks. The rates of abrasion and crack propagation were plotted on a log-log scale as a function of frictional and tearing energies, respectively. Reasonable agreement was observed, indicating that the major mechanism of the abrasion pattern involved repeated crack propagation.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.96-100
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• 1997

Hydrogenated amorphous carbon films were deposited on silicon substrates by using an RF PECVD. The hydrogen/methane ratio was varied from 50% to 88% to study the effect of hytdrogen in the film on the tribological properties. The friction and wear behaviors of the deposited films were investigated by ball-on-disk type wear tester. FT-IR spectra were used to characterize the structure of the films. Tribological properties of carbon films were correlated with their structure such as ratio of "polymer-like" stretching type and that of sp2 bonding. The result showed that the annealing caused a decrease in the amount of wear of contacted $Si_3N_4$ balls and a increase in the coefficient of friction. Possible explanation for annealing effect was discussed by the hydrogen desorption.esorption.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.39-42
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• 1999

Perfluoropolymers represent the ultimate resistance to hostile chemical environments and high service temperature, attributed to the presence of fluorine in the polymer backbone, i.e. to the high bond energy of C-F and C-C bonds of fluorocarbons. Copolymers of Tetrafluoroethylene (TEE) and 2, 2, 4Trifluoro-5Trifluorometoxy- 1, 3Dioxole (TTD), commercially known as HYFLON AD, are amorphous perfluoropolymers with glass transition temperature (Tg)higher than room temperature, showing a thermal decomposition temperature exceeding 40$0^{\circ}C$. These polymer systems are highly soluble in fluorinated solvents, with low solution viscosities. This property allows the preparation of self-supported and composite membranes with desired membrane thickness. Symmetric and asymmetric perfluoropolymer membranes, made with HYFLON AD, have been prepared and evaluated. Porous and not porous symmetric membranes have been obtained by solvent evaporation with various processing conditions. Asymmetric membranes have been prepared by th wet phase inversion method. Measure of contact angle to distilled water have been carried out. Figure 1 compares experimental results with those of other commercial membranes. Contact angles of about 120$^{\circ}$for our amorphous perfluoropolymer membranes demonstrate that they posses a high hydrophobic character. Measure of contact angles to hexandecane have been also carried out to evaluate the organophobic character. Rsults are reported in Figure 2. The observed strong organophobicity leads to excellent fouling resistance and inertness. Porous membranes with pore size between 30 and 80 nanometers have shown no permeation to water at pressures as high as 10 bars. However high permeation to gases, such as O2, N2 and CO2, and no selectivities were observed. Considering the porous structure of the membrane, this behavior was expected. In consideration of the above properties, possible useful uses in th field of gas- liquid separations are envisaged for these membranes. A particularly promising application is in the field of membrane contactors, equipments in which membranes are used to improve mass transfer coefficients in respect to traditional extraction and absorption processes. Gas permeation properties have been evaluated for asymmetric membranes and composite symmetric ones. Experimental permselectivity values, obtained at different pressure differences, to various single gases are reported in Tab. 1, 2 and 3. Experimental data have been compared with literature data obtained with membranes made with different amorphous perfluoropolymer systems, such as copolymers of Perfluoro2, 2dimethyl dioxole (PDD) and Tetrafluorethylene, commercialized by the Du Pont Company with the trade name of Teflon AF. An interesting linear relationship between permeability and the glass transition temperature of the polymer constituting the membrane has been observed. Results are descussed in terms of polymer chain structure, which affects the presence of voids at molecular scale and their size distribution. Molecular Dyanmics studies are in progress in order to support the understanding of these results. A modified Theodoru- Suter method provided by the Amorphous Cell module of InsightII/Discover was used to determine the chain packing. A completely amorphous polymer box of about 3.5 nm was considered. Last but not least the use of amorphous perfluoropolymer membranes appears to be ideal when separation processes have to be performed in hostile environments, i.e. high temperatures and aggressive non-aqueous media, such as chemicals and solvents. In these cases Hyflon AD membranes can exploit the outstanding resistance of perfluoropolymers.

• Macromolecular Research
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• v.12 no.1
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• pp.94-99
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• 2004

We have performed Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) studies on blends of poly(vinyl phenol) (PVPh) with poly(n-alkylene 2,6-naphthalates) containing alkylene units of different lengths. The results indicate that each poly(ethylene 2,6-naphthalate) (PEN) and poly(trimethylene 2,6-naphthalate) (PTN) blend with PVPh is immiscible or partially miscible, but blends of poly(butylene 2,6-naphthalate) (PBN) with PVPh are miscible over the whole range of compositions in the amorphous state. FTIR spectroscopic analysis confirmed that significant degree of intermolecular hydrogen bonding occurs between the PBN ester carbonyl groups and the PVPh hydroxyl groups. The large difference in the degree of mixing in these blend systems is described in terms of the effect that chain mobility has on the accessibility of the ester carbonyl functional groups toward the hydroxyl groups of PVPh, which in turn impacts the miscibility of these blends.