• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1015-1020
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• 2007

A simple approach to prepare arrays of Au/TiO2 composite nanoparticles by using Au-loaded block copolymers as templates combined with a sol-gel process is described. The organic-inorganic hybrid films with closely packed inorganic nanodomains in organic matrix are produced by spin coating the mixtures of polystyrene-block-poly(ethylene oxide) (PS-b-PEO)/HAuCl4 solution and sol-gel precursor solution. After removal of the organic matrix with deep UV irradiation, arrays of Au/TiO2 composite nanoparticles with different compositions or particle sizes can be easily produced. Different photoluminescence (PL) emission spectra from an organic-inorganic hybrid film and arrays of Au/TiO2 composite nanoparticles indicate that TiO2 and Au components exist as separate state in the initial hybrid film and form composite nanoparticles after the removal of the block copolymer matrix.

• Progress in Medical Physics
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• v.9 no.4
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• pp.207-215
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• 1998

There have been many radiation measurement methods so far among which film dosimetry, TLD, and ion chamber are the most frequently used methods. But this study describes a new radiation measurement method which uses polymer gel and magnetic resonance imaging(MRI). The objective of this study is to fabricate a polymer gel sensitive to radiation and to generate a dose to MRI contrast relationship, and to apply this results to the radiation measurement for the brachytherapy. To do this, 12 cm diameter cylindrical gel phantom was made, and the phantom was irradiated using the 30 mm diameter circular collimator which was used for radiosurgery. And this irradiated phantom was scanned with MRI. To find out the relationship between the radiation dose and the transversal relaxation time, an image processing software(IDL) was used. From this study it is found out that the radiation dose showed linear relationship to the transversal relaxation time of the gel up to 17 Gy($R^2$=0.993) and they had a different relationship above 17 Gy. The dose distributions were calculated using these results for the Ir-192 sources, one for the HDR afterloading system and the other for a 2 mCi seed source. And these calculated dose distributions were compared to the ones from the treatment planning computers. From this study the dose to the irradiated gel's transversal relaxation time relationship was examined, and this result was tried for the measurement of the brachytherapy.

• Polymer(Korea)
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• v.36 no.5
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• pp.617-621
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• 2012

PHEAs [${\alpha}$,${\beta}$-poly(2-hydroxyethyl-DL-aspartamides)], a class of poly(amino acid), have been widely studied as biodegradable and biocompatible polymers for potential biomedical and pharmaceutical applications. In this study, we investigated a homogeneous blend of PHEA with poly(N-vinyl pyrrolidone) (PNVP) and its semi-IPN (semi-interpenetrating polymer network) gels. Blend films were prepared by a solution casting method. The resulting blends were totally transparent over the whole composition ranges and the single $T_g$, changing monotonously with composition, was observed by DSC to confirm the miscibility between these two polymers. FTIR was used to discuss the possible hydrogen-bonding interaction between polymers. In addition, semi-IPN type gels were prepared by chemical crosslinking of PHEA/PNVP blend solution using hexamethylene diisocyanate (HMDI) as a crosslinking reagent. The prepared gel was characterized by their swelling property and morphology.

• Polymer(Korea)
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• v.30 no.6
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• pp.563-567
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• 2006

Poly(vinyl alcohol) (PVA) and gelatin (GEL) blend membranes were prepared by solution casting method under a high electric field. SEM observation of the membrane showed that gelatin rich domains were elongated and oriented to the direction of the applied electric field in PVA matrix. This can be attributed to the electrostatic emulsifying effects due to a reduction in interfacial tension. In addition, it was observed through WAXD and swelling measurements that the degree of crystallinity of membranes increased with applied electric field strength. This may be interpreted to be caused by the orientation effect of GEL domains in the blend membrane, and the self-annealing effect due to some heat generated from high electric field during casting.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.4
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• pp.274-278
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• 2001

Polymer membranes composed of N, N-dimethylaminoethyl methaccrylate(DMAEMA) and acrylamide(AAm)(or ethyl acrylamide(EAAm) were prepared to demonstrated the thermo-control of solute permeation. Poly DMEMA has a lower critical solution temperature(LCST) at around 50$\^{C}$ in water, With the copolymerization of DMAEMA with AAm (or EAAm) a shift in the LCST to a lowere temperature was observed, probably due to the formation of hydrogen bonds between the amide and N-N-dimethylamino groups. However, the temperature-induced phase transition of poly(DMAEMA-co-EAAm) did not show a similar trend to that of poly(DMAEMA- co-AAm) in the gel state. The hydrogen bonds in poly(DMAEMA-co-EAAm) were significantly disrupted with the formation a gel network, which led to a difference in the swilling behavior of polymer gels in response to temperature. To apply these polymers to temperature-sensitive sol-ute permeation, polymer membranes were prepared. The permeation pattern of hydrocortisone, used as the model solute, was explained based on the temperature-sensitive swelling behavior of the polymer membranes.

• Journal of the Korean Electrochemical Society
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• v.6 no.2
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• pp.141-144
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• 2003

Proton conducting polymeric gels as the electrolytes of electrochemical capacitors have been prepared by two different methods: 1) swelling a polymethacrylate-based polymer matrix in aqueous solutions of inorganic and organic acids, and 2) polymerizing complexes of anhydrous acids and prepolymers with organic plasticizer. The FT-IR spectra strongly suggest that the carbonyl groups in the polymer matrix interact with protons from the doped acids. High ionic (proton) conductivity in the range of $6\times10^{-4}-4\times10^{-2}\;S\;cm^{-1}$ was obtained at room temperature for the aqueous gels. The non-aqueous polymer complexes showed rather low ionic conductivity, but it was about $10^{-3}\;S\;cm^{-1}\;at\;70^{\circ}C$ for the $H_3PO_4$ doped polymer electrolyte. The mechanisms of ion (proton) conduction in the polymeric systems are discussed.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.199-199
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• 2010

Polymeric membranes have been widely used to separate gas mixtures, such as $O_2/N_2,\;CO_2/CH_4,\;CO_2/N_2$, and olefin/paraffin. The permeation selectivity is the ratio between composition ratio at the permeate side and composition ratio at the feed side. In addition, the permeation selectivity is a product of solubility selectivity and diffusivity selectivity. We present a novel idea and describe its experimental result, which was achieved by preparing polymer gel films that included a room temperature ionic liquid (RTIL) in a polymer matrix. It is known that $CO_2$ can dissolve easily in imidazolium-based RTILs. We prepared polymer-ionic liquid gel films using an ionic liquid, 1-ethyl-3-methylimidazolium acetate ([emim] acetate, C-tri) and a host polymer, poly (vinyl acetate) (PVAc, Aldrich).

• Macromolecular Research
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• v.9 no.5
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• pp.253-258
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• 2001

Crosslinked poly(ethylene glycol)s (PEGs) were prepared by ultraviolet irradiation of low molar mass, liquid PEGs in the presence of benzophenone (BP) as a photoinitiator. The networks obtained have been characterized by DSC, IR, and contact angle measurements, and their water absorption and equilibrium swelling have been examined. The percent of gel formed and degree of swelling of the networks in water were dependent on the amount of BP in the reaction mixture, irradiation time and molar mass of PEG. Gel fraction yield exceeded 84%, and equilibrium swelling in water varied from 49 to 244%.

• Macromolecular Research
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• v.17 no.1
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• pp.26-30
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• 2009

To modify and strengthen the properties of PHEMA hydrogel, composite hydrogels containing varying amounts of a Pluronic (PEO-PPO-PEO) component were synthesized by bulk polymerization of HEMA in the presence of Pluronic dimethacrylate under mild photo initiating conditions. The effects of the Pluronic component on gel properties were investigated by measuring the degree of swelling with its temperature responsive behavior, the mechanical properties, and the morphology of the composite hydrogels. With increased Pluronic content, the modified PHEMA hydrogels exhibited an increase in the degree of swelling, and the swelling showed an enhanced thermo-responsive behavior that was completely reversible. In addition, improved mechanical strength and the development of a microporous gel morphology were observed in hydrogels containing Pluronic.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.27-28
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• 2006

Chromatographic separation of enantiomers by high-performance liquidchromatography (HPLC) has considerably advanced in the past two, and many optically active polymers have been developed to be usedaschiral stationary phases (CSP). Among many CSPs, cellulose-andamylose-based CSPs are most attractive from the viewpoints of theirwide applicability and easy availability. The polysaccharides are readily modified to ester and carbamates. The derivatives have been used as CSPs after being coated on macroporus silica gel. Here, the CSPs based on phenylcarbamate derivatives of these two polysaccharides will be mainly discussed. The immobilization of the derivatives on silica gel will also be discussed.