• 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.

• Bulletin of the Korean Chemical Society
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• v.19 no.4
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• pp.444-449
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• 1998

The kinetics of the formation of triplex $poly(dA){\cdot}[poly(dT)]_2$ from poly(dA)·poly(dT) and poly(dT) is examined by various optical spectroscopic methods, including absorption, circular and linear dichroism (LD) spectroscopy. In the pseudo first order condition, where the poly(dT) concentration is kept lower than that of duplex, the association of the poly(dT) is enhanced by the presence of ethidium; the rate constant is proportional to the amount of ethidium in the mixture. When the concentration of the duplex and the single strand is the same, a spectral change is explained by double exponential curves, indicating that at least two steps are involved, the fast association and slow rearrangement steps. In contrast to the pseudo first order kinetics, the association step in an equimolar condition is not affected by the presence of ethidium. In the rearrangement step, the magnitude of LD decreases with an increase in ethidium concentration, suggesting that the bending of polynucleotide around the intercalation site occurs in the rearrangement step.

• Macromolecular Research
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• v.9 no.5
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• pp.277-284
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• 2001

Poly(exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride)s [poly(ETA)s] and poly($\alpha$-ethoxy-exo-3,6-epoxy-1,2,3,6-tetrahydrophthaloyl-5-fluorouracil)s [poly(EETFU)s ] with various average molecular weights were prepared by photopolymerizations. The number average molecular weights of the fractionated poly(ETA)s and poly(EETFU)s determined by GPC were in the range of 3,600∼21,000 and 3,600-33,400, respectively. The release rate of 5-FU from poly(EETFU) decreased with increasing average molecular weight. The in vitro cytotoxicity of poly(ETA) against a normal cell line was lower than that of 5-fluorouracil(5-FU), The in vivo antitumor activities of the synthesized samples at dosage of 0.8 mg/kg against mice bearing sarcoma 180 tumor cell line decreased in the following order: poly(EETFU) > poly(ETA) > EETFU > ETA > 5-FU. The antiangiogenic activities of the poly(ETA)s were better than those of 5-FU.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.316-321
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• 2008

Monodispersed particles of poly(styrene-co-4-vinylpyridine), poly(st-co-4vp) were prepared by soapless emulsion polymerization. Iron oxide was formed on the surface and inside of the poly(st-co-4vp) particles by thermal decompostion of iron pentacarbonyl. The obtained magnetic poly(st-co-4vp) particles was mondispersed and the average size was 250 nm. The magnetic poly(st-co-4vp) particles had 14% of iron oxide, which was identified as $Fe_3O_4$ by XRD. The magnetic poly(st-co-4vp) particles had superparamagnetism according to superconducting susceptometer (SQUID).

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.509-518
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• 2023

In this paper, we designed a 4Kb poly-fuse OTP IP (Intellectual Property) required for analog circuit trimming and calibration. In order to reduce the BL resistance of the poly-fuse OTP cell, which consists of an NMOS select transistor and a poly-fuse link, the BL stacked metal 2 and metal 3. In order to reduce BL routing resistance, the 4Kb cells are divided into two sub-block cell arrays of 64 rows × 32 rows, with the BL drive circuit located between the two 2Kb sub-block cell arrays, which are split into top and bottom. On the other hand, in this paper, we propose a core circuit for an OTP cell that uses one poly-fuse link to one select transistor. In addition, in the early stages of OTP IP development, we proposed a data sensing circuit that considers the case where the resistance of the unprogrammed poly-fuse can be up to 5kΩ. It also reduces the current flowing through an unprogrammed poly-fuse link in read mode to 138㎂ or less. The poly-fuse OTP cell size designed with DB HiTek 90nm CMOS process is 11.43㎛ × 2.88㎛ (=32.9184㎛2), and the 4Kb poly-fuse OTP IP size is 432.442㎛ × 524.6㎛ (=0.227mm²).

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.47-61
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• 1999

In this paper we difine poly-Euler numbers which generalize ordinary Euler numbers. We construct a p-adic poly-Euler measure by the poly-Euler polynomials and derive an integral formula.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.97-109
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• 2020

Membrane fouling is the main drawback of membrane technology. Frequent membrane cleaning and membrane replacement are, therefore, required to reduce membrane fouling that causes permeate flux reduction, lower rejection, or higher operating pressure. Studies have proved that the alteration of membrane properties is the key controlling factor in lessening membrane fouling. Among stimuli-responsive membranes, thermo-responsive membrane is the most popular, with a drastic phase transition and swelling-shrinking behavior caused by the temperature change. In this study, the thermo-responsive ability of two commercial membranes, PolyCera® Titan membrane and PolyCera® Hydro membrane, at different temperatures was studied on the antifouling function of the membrane in palm oil mill effluent (POME) treatment. The evaluation of the membrane's thermo-responsive ability was done through three cycles of adsorption (fouling) and desorption (defouling) processes in a membrane filtration process. The experimental result depicted that PolyCera® Hydro membrane had a higher membrane permeability of 67.869 L/㎡.h.bar than PolyCera® Titan membrane at 46.011 L/㎡.h.bar. However, the high membrane permeability of PolyCera® Hydro membrane was compensated with low removal efficiency. PolyCera® Titan membrane with a smaller mean pore size had better rejection performance than PolyCera® Hydro membrane for all tested parameters. On the other hand, PolyCera® Titan membrane had a better hydrodynamic cleaning efficiency than PolyCera® Hydro membrane regardless of the hydrodynamic cleaning temperature. The best hydrodynamic cleaning performed by PolyCera® Titan membrane was at 35℃ with the flux recovery ratio (FRR) of 99.17 ± 1.43%. The excellent thermo-responsive properties of the PolyCera® Titan membrane could eventually reduce the frequency of membrane replacement and lessen the use of chemicals for membrane cleaning. This outstanding exploration helps to provide a solution to the chemical industry and membrane technology bottleneck, which is the membrane fouling, thus reducing the operating cost incurred by the membrane fouling.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.346-352
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• 2000

We investigated the oxidation behavior of poly $Si_{1-x}Ge_x$ films (X=0.15, 0.42) at $700^{\circ}C$ in wet oxidation ambients and analyzed the oxide by XPS, RBS, and cross-sectional TEM. In the case of poly $Si_{0.85}Ge_{0.15}$ films, $SiO_2$ was formed on the poly $Si_{1-x}Ge_x$ films and Ge was rejected from growing oxide, subsequently leading to the increase of Ge content. In the case of poly $Si_{0.58}Ge_{0.42}$ films, we found that $SiO_2-GeO_2$ were formed on the poly $Si_{1-x}Ge_x$ films due to high Ge content. Finally, we proposed the oxidation model of poly $Si_{1-x}Ge_x$ films.

• Macromolecular Research
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• v.8 no.1
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• pp.26-33
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• 2000

A series of pH/temperature sensitive polymers were synthesized by copolymerizing N-isopro-pyl acrylamide(NIPAAm) and acrylic acid(AAc) . The influence of polyelectrolyte between poly(allyl amine) (PAA) and poly(L-lysine)(PLL) on the lower critical solution temperature(LCST) of pH/temperature sensitive polymer was compared in the range of pH 2∼12. The LCST of PNIPAAm/water in aqueous poly(NIPAAm-co-AAc) solution was determined by cloud point measurements. A polyelectrolyte complex was prepared by mixing poly(NIPAAm-co-AAc) with poly(allyl amine) (PAA) or poly(L-lysine) (PLL) solutions as anionic and cationic polyelectrolytes, respectively. The effect of polyelectrolyte complex formation on the conformation of PLL was studied as a function of temperature by means of circular dichroism(CD). The cloud points of PNIPAAm in the aqueous copolymers solutions were stongly affected by pH, the presence of polyelectrolyte solute, AAc content, and charge density. The polyelectrolyte complex was formed at neutral condition. The influence of more hydrophobic PLL as a polyelectrolyte on the cloud point of PNIPAAm in the aqueous copolymer solution was stronger than that of poly(allyl amine)(PAA). Although polymer-polymer complex was formed between poly(NIPAAm-co-AAc) and PLL, the conformational change of PLL did not occur due to steric hinderance of bulky N-isopropyl groups of PNIPAAm.

• Polymer(Korea)
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• v.24 no.4
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• pp.477-487
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• 2000

A series of poly(L-lactic acid) (PLLA)/poly($\beta$-hydroxynonanoate) (PHN) blend were prepared to study the miscibility and the crystallization behaviors. The thermal behaviors and characterization of PLLA/PHN blends Were studied using differential scanning calorimetry (DSC), XRD and polarizing optical microscopy (POM). The PLLA and PHN are partially miscible in amorphous region. The crystallinity of PLLA increased as the content of PHN increased, and T$_{g}$, T$_{c}$, and T$_{m}$ of PLLA shift as the content of PHN increased. Moreover, the number of PLLA spherulite increased as the content of PHN increased in the POM experiment. Thus, PHN acted as a nucleating agent to PLLA.