• Macromolecular Research
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• 제14권2호
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• pp.209-213
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• 2006

The ring-opening polymerization of D,L-lactide initiated by tin(II) 2-ethylhexanoate $(Sn(Oct)_2)$ on the surface-initiated magnetite $(Fe_{3}O_4)$ nanoparticles was performed at $130^{\circ}C$. The effects of the polymer molar mass and concentration on the amount of surface polymer were investigated. The number average molecular weights, $M_n$, obtained by both NMR and GPC methods fit well within the accuracy of the applied methods and ranged from 1,100 to $4,040g\;mol^{-1}$. A surface functionalization density of up to 625 initiation sites per particle was obtained. The composition of various core-shell particles was determined by TGA, with results indicating magnetite $(Fe_{3}O_4)$ contents, ${\mu}m$, between 17 and 59 wt%. Under the influence of a magnetic field, the heating generated by superparamagnetic core-shell particles suspended in toluene presented guidelines for an optimization of magnetic particle systems with respect to an application for hyperthermia.

• Macromolecular Research
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• 제10권2호
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• pp.103-107
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• 2002

High purity water soluble chitosans (WsCs) were employed as a flocculant to remove heavy metal ions from wastewater of industrial plating wastewater treatment complex. Their weight average molecular weights and polydispersities were 272,000~620,000 g/mol and 1.4~1.9 range, respectively and were readily soluble in water in the pH range of 3~11. Heavy metal ions such as chromium, iron and copper were removed well by WsCs. When WsCs was blended with either sodium N, N-diethyldithiocarbamate trihydrate (SDDC$_{T}$) or sodium salicylate (SSc), the removal efficiency was further increased primarily due to the excess amount of hydrophilic sulfonic and carboxylic groups. Especially, in the case of WsCs-SSc the remaining chromium and copper concentrations were 0.1 mg/L and 9.5 mg/L, which are 1/15 and 1/3 compared with that of pure WsCs, respectively. The former is within the acceptable limit, but the latter is not. Therefore, the effective copper flocculant remains to be studied.d.

• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.67-78
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• 2006

Modification of polylactic acid (PLA) and 10% maleic anhydride (MAH) with 15% dicumyl peroxide (DCP) based on MAH weight was conducted in the kneader at $160^{\circ}C$ and 30~70 rpm, for 15 min. The resulting MAH-modified PLA (PLA-MA) was then evaluated as a compatibilizer for PLA-wood flour (WF) composites. The FTIR and $^1H$-NMR analysis gave evidence of PLA-MA formation. After kneading and reacting with MAH and DCP, the number (Mn) and the weight average (Mw) molecular weights of PLA decreased as compared to the original PLA. The presence of WF in the composites decreased the tensile strength and several other physical properties. The higher the WF loading resulted in the greater the reduction of tensile strength. An addition of 10% PLA-MA as a compatibilizer to the composites improved the tensile strength and several other physical properties, increased the flow temperature, and decreased the melt viscosity. The improved composite revealed 1.42 times increased in tensile strength but not over PLA alone, and absorbed considerably less water compared to those of the composites free-compatibilizer.

• Bulletin of the Korean Chemical Society
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• 제29권1호
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• pp.135-138
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• 2008

Two bicarbazyl-containing fluorene copolymers, PFEBCz (95/5) and PFEBCz (75/25), were synthesized for white light electroluminescence from a single emitting polymer. All synthesized polymers were soluble in common organic solvents such as chloroform and toluene. The weight-average molecular weights (Mw) of the PFEBCz (95/5) and PFEBCz (75/25) copolymers were found to be 11,000 and 5,700 with polydispersity indices 1.4 and 1.8. The EL spectrum of the PFEBCz (75/25) device showed bright white-light emission with CIE coordinates of (0.32, 0.34) at 1000 cd/m2, which is very close to that for pure white (0.33, 0.33). This white emission may have been due to strong excimer formation between the bicarbazyl and fluorene polymer backbone. The device exhibited a maximum brightness of 3400 cd/m2 with a maximum efficiency of 0.2 cd/A.

• Polymer(Korea)
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• 제27권5호
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• pp.443-448
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• 2003

2-Biphenylyl acrylate (BPA) was synthesized by the reaction of 2-phenylphenol as a microbicide with acryloyl chloride, and copolymers with the moiety of 2-phenylphenol were prepared by the radical terpolymerization of BPA-methylmethacrylate-acrylic acid. The contents of BPA unit in the poly mers were found to be 4.2 mol% and 9.1 mol% from their nuclear magnetic resonance spectra. The number average molecular weights of the polymers were in the range of 15000 to 16000. 2-Phenylphenol was released through the hydrolysis of the polymers. The release rate of the microbicide increased with increasing pH of the release medium. The released solution showed higher microbicidal activity for E. coli as a negative microbe than S. aureus as a positive microbe.

• Bulletin of the Korean Chemical Society
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• 제24권7호
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• pp.943-947
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• 2003

We have studied the migration behavior of single-stranded DNA using capillary gel electrophoresis under various conditions. It was found that optimum electric fields should be less than 150 V/cm for the good tradeoff between the separation time and the resolution. It seems that the gel matrix with the combination of different polymer average molecular weights is important to extend the maximum readable DNA bases. The total gel concentration less than 3.1% in the mixed gel system showed good separation efficiency up to 600 bases. The best result was obtained with the poy(ethylene)oxide (PEO) gel concentration of 1.2% of Mr 8,000,000 and 1.8% of Mr 600,000. We observed that the capillary length between 50 cm to 100 cm (effective length) should be employed for the optimization between the total DNA migration time and the maximum readable length. A trizma base-boric acid-ethlyenediaminetetraacetic acid (EDTA) (TBE) buffer was commonly used for DNA sequencing, but we found that 3-[tris(hydroxymethyl)methyl amino]-1-propane sulfonic acid (TAPS) buffer worked as well for the single-stranded DNA separation. Especially, TAPS buffer showed a good resolution for very short DNA bases (1 to 30 bases).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제19권6호
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• pp.568-573
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• 2006

We have synthesized new blue light emitting random copolymers, poly(9,9'-n-dioctylfluorene-co-perfluorobenzene-1,4-diyl)s (PFFBs), via Ni(0)-mediated coupling reactions. The weight-average molecular weights ($M_w$) of the PFFB copolymers ranged from 9,000 to 15,000. The PFFB copolymers dissolved in common organic solvents such as THF and toluene. The PL emission peaks of the PFFB copolymers were at around 420, 440, and 470 nm. EL devices were fabricated in ITO/PEDOT/polymer/Ca/Al configurations using these polymers. These EL devices were found to exhibit pure blue emission with approximate CIE coordinates of (0.15, 0.11) at $100cd/m^2$. The blue emissions of these devices might be due to the restriction of the polymer chains to aggregation by introducing of the highly electronegative fluorine moieties. The maximum brightnesses of the PFFB copolymer devices ranged from 140 to $3600cd/m^2$ with maximum efficiencies from 0.2 to 0.6 cd/A. The enhanced efficiency of the PFFB (8/2) copolymer device results from the inhibition of excimer formation by the introduction of the electronegative fluorine moieties into the copolymers.

• Macromolecular Research
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• 제11권1호
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• pp.47-52
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• 2003

The objective of this study was to develop a polymeric drug delivery system for camptothecin (CPT), capable of improving its therapeutic index and reducing its side effects. A monomeric conjugate, 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidoethanoylcamptothecin in (ETECPT) between CPT and 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidoethanoic acid was synthesized. Its homo-and copolymer with acrylic acid (AA) were prepared by photopolymerization using 2,2-dimethoxy-2-phenylacetophenone (DMP) as a photoinitiator. The monomer and its polymers were characterized by IR, $^1$H- and $^{13}$ C-NMR spectra. The ETECPT content in poly(ETECPT-co-AA) obtained by elemental analysis was 82 wt%. The number-average molecular weights of the polymers determined by gel permeation chromatography were as follows: M$_{n}$ = 11,400 for poly(ETECPT), M$_{n}$ = 17,900 for poly(ETECPT-co-AA). The $IC_{50}$/ values of ETECPT and its polymers against cancer cells were much larger than that of CPT. Our results from the in vivo antitumor activity indicated that all polymers show high antitumor activity than CPT at a dose of 100 mg/kg./kg.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.719-724
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• 1994

Major cellulase components, such as three endoglucanases (endoglucanases I, II, and III) and one exoglucanase (exoglucanase II), were isolated from a commercial cellulase (Meicelase TP 60) derived from the fungus Trichoderma viride by a series of chromatography procedures. These procedures were the gel filtration on Bio-Gel, the anion exchange on DEAE-Bio-Gel A, the cation exchange on SP-Sephadex C50, and the affinity chromatography on Avicel cellulose. The average molecular weights determined by SDS-polyacrylamide gel electrophoretic analysis were 51,000, 59,000, 41,000 and 62,000 Da for endoglucanases I, II and III and exoglucanase II, respectively. The extinction coefficients, ${\varepsilon}^{1%}$ 280 nm, of these enzymes were 11.7, 3.3, 7.2 and 11.3, respectively. Among them, the endoglucanase II showed the very low value of the coefficient compared with the others. On the other hand, it was found that endoglucanase II and III were of more random hydrolytic mode on carboxymethylcellulose as compared with those of endoglucanase I and exoglucanase II. Especially, endoglucanase I showed less random action than that of exoglucanase II. In the hydrolysis of insoluble cellulose by the enzyme components, cellobiose was the major product, but glucose was the major product by endoglucanase III.

• Textile Coloration and Finishing
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• 제31권2호
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• pp.77-87
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• 2019

To improve rubbing fastness of the printed fabrics, the binder polymers for Digital Textile Printing(DTP) pigment inks were synthesized with miniemulsion polymerization using various acrylic monomers, which are MMA(Methyl methacrylate), BA(Butyl acrylate), and Self-crosslinking monomers, such as NEA(N-Ethylol acrylamide) and MAA (Methacrylic acid). The acrylic monomer compositions were varied when synthesizing the binder polymers and their particle size distributions, average molecular weights, and Tgs were investigated. The prepared binder polymers were applied to prepare Cyan, Black, Yellow and Magenta pigment ink for DTP and the prepared inks were used to dye cotton fabrics. Then, color strength, and rubbing fastness were also investigated to study the effect of the comonomer compositions of the binder polymer on the color strength and rubbing fastness of the resulting pigment inks.