• Current Applied Physics
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• v.18 no.12
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• pp.1546-1552
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• 2018

The polymer nanocomposite as a gate dielectric film was prepared via sol-gel method. The formation of crosslinked structure among nanofillers and polymer matrix was proved by Fourier transform infrared spectroscopy (FT-IR). Differential thermal analysis (DTA) results showed significant increase in the thermal stability of the nanocomposite with respect to that of pure polymer. The nanocomposite films deposited on the p- and n-type Si substrates formed very smooth surface with rms roughness of 0.045 and 0.058 nm respectively. Deconvoluted $Si_{2s}$ spectra revealed the domination of the Si-OH hydrogen bonds and Si-O-Si covalence bonds in the structure of the nanocomposite film deposited on the p- and n-type Si semiconductor layers respectively. The fabricated n-channel field-effect-transistor (FET) showed the low threshold voltage and leakage currents because of the stronger connection between the nanocomposite and n-type Si substrate. Whereas, dominated hydroxyl groups in the nanocomposite dielectric film deposited on the p-type Si substrate increased trap states in the interface, led to the drop of FET operation.

• Polymer(Korea)
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• v.32 no.5
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• pp.415-420
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• 2008

The porcine small intestinal submucosa (SIS) without immunorejection responses and hyalunonic acid (HA) can be used as biomaterials. In this study, we tried to design and characterize novel sponge. SIS- HA sponge was prepared by freeze-drying after addition 1wt% HA solution into fabricated SIS sponge. Sponge was crosslinked with 1-ethyl-(3-3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) solution with 100mM concentration for 24 hrs and lyophilized. SIS-HA sponge was characterized by scanning electron microscopy and fourier transform infrared spectrometer. And water absorption ability of sponge was evaluated. We seeded NIH/3T3 cells in SIS-HA sponge and cellular attachment was assayed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltertazolium-bromide (MTT) test. We demonstrated presence of HA in SIS-HA sponge from C-O functional group observed by the FT-IR analysis. Moreover, we confirmed low cytotoxicity and high cell viability of the SIS-HA sponges. Therefore, we could expect that SIS- HA scaffolds are applicable for the tissue regeneration.

• Polymer(Korea)
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• v.27 no.3
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• pp.195-200
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• 2003

Alginate is a natural ionic polymer including numerous anionic groups and can be actuated by the ionic group under the electric field. The crosslinked alginate films were fabricated with CaCl$_2$. The thermal, mechanical and electroresponse properties of the films were investigated by thermogravimetric analysis, tensile and bending tests. The initial degradation and tensile strength increased according to the degree of crosslinking. Also, the swelling ratio of the films increased with decreasing degree of crosslinking and increasing pH due to free volume and electrostatic repulsion. The films actuated by an electric stimulus exhibited gentle and flexible action like a pendulum. In the electric field, the electric stimuli such as the applied voltage, ionic strength and kind of electrolyte solution had an effect on the electroresponse of the films. Alginate films with 5 wt% crosslinking agent showed the highest bending angle and reversible bending behavior. When the ionic strength of NaCl and KCl electrolyte solution was 0.1 M, the films showed the highest electroresponse. The bending behavior of the films increased with the applied voltage.

• Polymer(Korea)
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• v.25 no.5
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• pp.736-743
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• 2001

An electro- active polymer (EAP) (poly(2-acrylamido-2- methyl propane sulfonic acid), PAMPS) gel crosslinked with N,N-methylenebisacrylamide (MBAA) has been prepared by free radical polymerization in aqueous solution with potassium persulfate as initiator PAMPS gel was swollen in surfactant solution to substitute surfactant for using as actuator. PAMPS gel showed a large movement in the surfactant solution by electric field. PAMPS gel showed the reversible binding and fast response rate. Bending mechanism of gel is related to the cooperative process of hydrophobic interaction, swelling-deswelling of gel and the electrostatic attraction between anode (+) and the anions of PAMPS gel. The response rate of PAMPS gel was increased as the applied potential and the degree of cross-linkage were increased. The response rate was increased as the bending cycle was repeated, but it was decreased with increasing the gel thickness.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1064-1067
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• 2012

Recently, there is a growing interest in vegetable oils, cheap and abundant renewable natural resources. Vegetable oils can be used as raw materials for ecofriendly biodegradable polymer materials. In this study, poly(${\beta}$-amino esters) were synthesized by polymerization reaction of acrylated epoxidized soybean oil (AESO) and 2-aminoethanol. Various polymer films were prepared by changing the molar ratio of AESO to 2-aminoethanol. The formation of C-N bonds in poly(${\beta}$-amino ester) was confirmed using FT-IR. Gel contents higher than 98% confirmed the synthesis of crosslinked polymer networks. Tensile strengths and elongation at breaks of polymer films ranged from 0.3 to 1.3 MPa and 32 to 55%, respectively. Polymer films degraded 2 to 7% of the initial weight in 35 days in phosphate buffer solution (pH 7.2) containing lipase enzyme.

• Polymer(Korea)
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• v.38 no.2
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• pp.199-204
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• 2014

To prepare acrylic pressure sensitive adhesives (PSAs), quaternary copolymer syrups were photopolymerized from 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate as default constituents and isobornyl acrylate and tetrahydrofurfuryl acrylate (THFA) as variable constituents. After polymerization, 1,6-hexanediol diacrylate and photoinitiator were added and then crosslinked by UV-irradiation to prepare the PSAs. The characteristics of the syrup such as viscosity, molecular weight, and solid content were investigated. As increasing THFA contents, the relationship between molecular weight and solid content of the syrup was reciprocal. Also, the relationship between peel strength and surface energy of the PSAs showed the same tendency. All the PSA samples showed high transmittance (more than 92%), low haze (less than 1.0%) and low color-difference (less than 1.0).

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.6
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• pp.782-790
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• 2000

The mainly used polymeric material for the denture is PMMA because of its cost and easiness to handle. So it was widely used material among dentists for past decades. But the acrylic-based denture materials have several common weak points such as shrinkage after curing and lack of strength. In order to solve these problems, we adapted one of hybrid system using acrylic polymer and vinyloligosilsesquioxane(POSS). POSS, which is a well known expandable monomer during polymerization process, may eventually suppress volumetric shrinkage. And the hybrid system makes it possible for the polymer to be stable in various severe conditions. Eight different kinds of samples were designed and synthesized. Each samples were characterized with dynamic mechanical analyser(DMA) to confirm their thermodynamic properties, fractured to analyze the cross-sectional morphology of the samples. And elongation, flexural and impact tests were also executed to evaluate the mechanical properties of the samples. From the results, hybrid composites had well defined crosslinked network structure compared to the widely used denture materials, and the mechanical strength improved without changing any surface condition as increment with POSS ratio in hybrid system. Fractured morphology showed homogeneous surfaces in spite of mutli component system, therefore we can conclude that the adoption of the POSS brought the reinforcement of the denture resin.

• Polymer(Korea)
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• v.35 no.6
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• pp.558-564
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• 2011

The biocompatibility and biodegradability of poly(amino acid) make them ideal candidates for many bio-related applications. Poly(aspartic acid), PASP, is one of synthetic water-soluble polymers with proteinlike structure, and has been extensively explored for the potential industrial and biomedical applications due to its biodegradable, biocompatible and pH-responsive properties. In this work, amino acid-conjugated PASPs were prepared by aminolysis reaction onto polysuccinimide (PSI) using ${\gamma}$-aminobutylic acid(GABA) and ${\beta}$-alanine methyl ester and a subsequent hydrolysis process. Their chemical gels were prepared by crosslinking reaction with ethylene glycol diglycidyl ether (EGDE). The hydrogels were investigated for their basic swelling behavior, hydrolytic degradation and morphology. The crosslinked gels showed a responsive swelling behavior, which was dependent on pH and salt concentration in aqueous solution, and relatively fast hydrolytic degradation.

• Polymer(Korea)
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• v.33 no.2
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• pp.131-136
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• 2009

The effect of the chemical structure of the peroxide crosslinking agent on the reactive crosslinking reaction of EVA was investigated and the physical properties of the crosslinked EVA were studied as well. It was found that peroxide with one peroxy group (perbutyl peroxide) is more effective than peroxides with two peroxy group (2,5 dimethyl 2,5 di(tert-butylperoxyl) hexane and 1,1-di(tert-buthylperoxy)-3,3,5-tri-methylcyclohexane) in melt reactive crosslinking reaction of EVA. The rate of crosslinking was increased by the use of crosslinking acceleration agent but the noticeable effect on degree of crosslinking was not found. Crosslinking caused the lowering of melt flow ability of EVA but mechanical properties were enhanced by the crosslinking of EVA.

• Journal of Adhesion and Interface
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• v.20 no.2
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• pp.66-70
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• 2019

The surface of hydrophobic polypropylene (PP) fibers (spun-bonded fabric) was treated by an atmospheric plasma treatment method. These pre-treated hydrophilic PP fabrics were dip-coated in the aqueous poly(N-vinyl pyrrolidone) (PVP) solution. PVP layers on the surface of PP fiber were crosslinked by an irradiation of electron beam. The thickness of PVP hydrogels coated on the surface was easily controlled by changing the concentration of PVP in coating solution. The stepwise surface treatment, PVP coating, and hydrogel formation via electron beam irradiation were analyzed by the measurement of contact angle, scanning electron microscopy, and optical microscopy.