• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.91-101
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• 2002

An acid amplifier is defined as an acid-generating agent which is decomposed autocatalytically to produce new strongly acidic molecules in a non-liner manner, The addition of the acid amplifiers to conventional chemically amplified photoresists consisting of photoacid generators and acid-sensitive polymers result in the improvement of photosensitivity due to the amplified generation of catalytic acid molecules as a result of the decomposition of acid amplifiers. We synthesized and evaluated 1-hydroxy-4-tosyloxy cyclohexane(AA-1) and 1,4-ditosyloxy cyclohexane(Ah-2) as novel acid amplifiers. The acid amplifiers(AA-1, AA-2) showed reasonable thermal stability for resist processing temperature. As estimated by the sensitivity curve, tort-butyl methacrylate homopolymer(ptBMA) film doped with AA-1 or 2 exhibited much higher photosensitivity than ptBMA film without AA-1 or 2. And AA-1 showed higher effect than AA-2 on enhancing photosensitivity of ptBMA film.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.199-204
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• 1987

ABA type block copolymers composed of r benzyle L-glutamate as the A component and poly(ethylene glycol) as the B components were obtained. Platelet adhesion on their sunfaces was investigated by a column elusion method to examine the effects of microdomain and secondary structure. The number of platelets adhered from whole blood and plasma rich platelet was smaller for the block copolymer systems than for the homopolymers. In the block copolymer system, the number of platelets adrered on their surfaces increased with increasing the content of PEG, that is, with decreasing of a-helix of block copolymers. A thick thrombus formation on the PBLG homopolymer was observed than block copolymer by scanning electron micrographs. The platelets adhesion increased with increasing the critical surface tension of the block copolymer.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.237-242
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• 1989

The physical properties and drug release behaviours of polyethylene glycol grafted poly ${\gamma}$- benzyl L-glutamate (PEG- g- PBLG), polyethylene glycol crosslinked poly ${\gamma}$-benzyl L- glutamate(PEG-c-PBLG), and PBLG homopolymer are compared. PBLG containing PEG segements showed higher wettability and larger enlongation than PBLG homoplymer, but lower elastic modulus. The release rate of rhodamine is strongly influenced by the wettability of the polymer. Rhodamine is more rapidly released from PEG-c-PBLG membrane having a larger water contact angle than from other polymer having a lower water contact angle. The surfaces of PBLG derivative membranes are modified by substitution reaction using hydroxyalkylamine. The resulting polymer membranes showed hider wettability and swelling ratio than virgin membranes.

• Elastomers and Composites
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• v.24 no.3
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• pp.185-192
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• 1989

The thermal degradation of the homopolymer poly(methyl methacrylate)(PMMA)/tetra cyano quino dimethane(TCNQ) blend and Eccogel/TCNQ blend were carried out using the thermogravimetric method in the stream of nitrogen gas with 60ml/min at various heating rate from 1 to $20^{\circ}C/min$. Friedman and Ozawa mathermatical methods were used to obtain the value of activation energy. Produced electrical properties and activation energy by electric conductivity method that used LCR meter.

• Fibers and Polymers
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• v.2 no.1
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• pp.123-130
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• 2001

Photoresponsive side chain copolymer and homopolymer containing an aminonitroazobenzene were synthesized for studying photoisomerization behavior and photo-induced anisotropy. Trans-to-cis photoisomerization was observed under the exposure of a circularly polarized visible light with UV-Vis absorption spectroscopy. Reorientation of polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532nm. Polarized absorption spectroscopy was employed to investigate the anisotropy of the polymer film during irradiationg of the excitation light. Layers of two photosensitive polymers were used for aligning liquid crystal(LC) molecules instead of one of the rubbed polyimide layers in the conventional twisted nematic cell. For producing homogeneous alignment of a nematic LC molecule, a linearly polarized light was exposed to the films of two polymers. The stability of the LC alignment upon the linearly polarized light exposure was also studied.

• Advances in materials Research
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• v.1 no.4
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• pp.269-284
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• 2012

Thermoresponsive hydrogels based on N-Isopropylacrylamide (NIPAM) and 2-Hydroxyethylacrylate (HEA) were prepared by free radical polymerization. The hydrogels were characterized by elemental (CHN) analysis, differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). DSC thermogram showed two endothermic transitions which are due to hydration of water present in different environments. One near $0^{\circ}C$ called melting transition of ice and was used to calculate the quantitative determination of the amounts of freezing and non freezing water. The other transition above the ambient temperature was due to the combination of hydrophobic hydration and hydrophilic hydration which changes with the copolymer compositions. Swelling and deswelling studies of the hydrogels were carried out using the aqueous media, salt and urea solutions. The experimental results from swelling studies revealed that copolymers have lower rates of swelling and deswelling than the homopolymer.

• The International Journal of Costume Culture
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• v.6 no.2
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• pp.134-146
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• 2003

Polyester of linear homopolymer poly(ethylene terephthalate)(PET) was chemically modified through the formation of branched copolymer to improve the undesirable properties of fiber. Photo-induced graft copolymerization of the acrylic monomers acrylic acid (AA) and methyl acrylate (MA) in the liquid and vapor phase, respectively, onto N,N-dimetylformamide (DMF)-pretreated PET fibers was carried out. The effect of various synthesis conditions and DMF pretreatment of the PET on the graft yield was investigated. Grafting mechanism was analysed. The grafting was promoted by increasing DMF pretreatment temperature and amount of DMF retention in the fiber. The increasing biacetyl and monomer flow time, and irradiation time enhanced the grafting up to a certain amount and thereafter it decreased.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.53-54
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• 1994

Polyimide는 열, 화학적으로 안정하고 기계적성질이 우수하고, 기체분리특성이 비교적 좋다. Polyimide의 화학구조와 기체투과도와의 관계는 화학구조를 체계적으로 변화시키면서 많이 검토되어왔다.[1-2] Polyimide는 강직한 직쇄구조, bulky group에 의한 분자쇄운동성을 제어함과 동시, 약한 분자간 상호작용이 polymer chain의 유효층진을 억제하여 기체투과도를 높여준다. 국부분절운동(local segmental mobility)이 감소된 구조는 기체투과선택도를 향상시켜주는 경향을 보여주었다. [3] kim et al. 과 Stern et al은 6FDA나 fluorine-containing diamines으로 만든 polyimde가 매우높은 투과도를 보여준다고 보고했다. 본 연구에서는 6FDA-2, 4TDA hobopolymer에 BAAF를 가하여 copolyimide Membrane을 제막하여 BAAF 조성에 따라 투과선택도를 측정하는 homopolymer와 copolymer에 따른 변화를 관찰하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.277-278
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• 2003

키틴은 셀룰로오스와 더불어 자연계에 가장 많이 존재하는 천연고분자(선형다당)로서 $\beta$(1$\longrightarrow$4)-2-deoxy-2-acetamido-D-glucopyranose를 기본단위로 하고, 키토산(chitosan)은 천연적으로는 몇몇 미생물에서 발견되며, 키틴의 탈아세틸화반응(deacetylation)에 의해 생성되는 유도체로서 $\beta$(1$\longrightarrow$4)-2-deoxy-2-amino-D-glucopyranose를 기본단위로 한다는 점에서 상이하다. 하지만 키틴과 키토산은 각 기본단위가 반복된 homopolymer가 아니고 서로 일정 정도의 상대 기본단위를 함유하므로 일종의 공중합체 또는 heteropolymer라고 할 수 있으며, 그 조성비 즉 탈아세틸화도 (degree of deacetylation, 이하 DD)에 따라 키틴과 키티산으로 나누어진다.[1] (중략)

• Macromolecular Research
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• v.8 no.6
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• pp.261-267
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• 2000

It is well known that poly(cyclohexylene dimethylene terephthalate) (PCT) is used as the engineering plastics with high melting temperature and fast crystallization rate compared with poly(butylene terephthalate)(PBT). However, poor thermal stability of PCT has limited its practical application due to the drastic decrease of molecular weight during the processing temperature. In order to improve the thermal stability of PCT homopolymer, the copolymer of PCT and PBT was synthesized and the thermal properties of the copolymer have been studied. P(CT/BT) copolymer was obtained by condensation polymerization of DMT, CHDM, and 1,4-butanediol. The chemical structure and composition of the copolymer was investigated by FTIR and NMR analysis. The thermal behavior of copolymer was studied using DSC and it was found that the crystallization-melting behavior of the copolymer was observed for the whole composition range. TGA analysis exhibited that P(CT/BT) copolymer is more stable at the initial stage of thermal decomposition compared with PCT and PBT homopolymers.