• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.269-279
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• 1975

Photosensitive properties of naphthoquinone-1,2-diazide-5-sulfonyl esters (PGND, BEND and PVAND) of polyglyceryl phthalate(PG), bisphenol A-epichlorohydrin condensate(BE) and polyvinyl alcohol(PVA) were investigated by the change of solubility before and after exposing to light. Various samples coated on glass or quartz plates were exposed to light under various conditions and steeped in aqueous alkali solution, and then the yield of residual film(W/W0) was determined. The yield of residual film, which was closely related to the sensitivity of the film, was affected by the degree of polymerization of the backbone resin, sensitizers and their concentration. In polymer homologs, the sensitivity was dependent on the degree of polymerization(the higher, the better). And also, it was most effective when 5 % of sensitizers to esters was used. The minimum exposed time was 0.6 min. for PGND-1, 1.0 min. for BEND-1, and 3.0 min. for PVAND-1. Most effective sensitizers for PGND, BEND and PVAND among those used here were benzanthrone, 5-nitroacenaphthene and picramide, respectively. The spectral sensitivities of PGND, BEND and PVAND were examined by comparing their spectrograms with UV-spectra in a solid state. Also, the sensitization and spectral sensitivity of the above polymers were studied. All the polymers containing the sensitizers showed optical sensitization. From the fact that in either case of sensitized or unsensitized sample, the ranges of absorption-maximum wave length were almost consistent with sensitivity maximum wave length, it was proved that the light absorbed by a sample served efficiently for photochemical reactions. Benzanthrone was found to be an excellent sensitizer for PGND.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.78-82
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• 2015

Hollow silica particles were prepared using sodium silicate and organic templates. Polystyrene latex (PSL) particles produced by dispersion polymerization were used as organic templates. PSL particles ranged from $1{\mu}m$ to $3{\mu}m$ in diameter were synthesized by adjusting the amount of 2,2'-azobisisobutyronitrile (AIBN). The PSL/$SiO_2$ core-shell particles were prepared by coating of silica nanoparticles originated from sodium silicate using sol-gel method. The organic templates were removed by the organic solvent, tetrahydrofuran (THF). Morphology of hollow silica particles was investigated with respect to types of the reaction medium and pH during the process. By changing the solvent from ethanol to water, hollow silica particles were successfully formed. Hollow silica particles with the uniform shell thickness were produced at low pH as well. The reflectivity of the as-prepared silica particles was measured in the range of the wavelength of UV and visible light. Hollow silica particles showed much better reflective properties than the commercial light reflector, Insuladd.

• Polymer(Korea)
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• v.36 no.2
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• pp.223-228
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• 2012

Temperature and pH sensitive graft copolymers [Pluronic-$g$-poly(NIPAAm-$co$-MMA), Polymer A] and [Pluronic-$g$-poly( NIPAAm-$co$-MAA), Polymer C] were synthesized by macro radical graft polymerization with $N$-isopropylacrylamide (NIPAAM)/$N,N$-diethylaminoethylmethacrylate (DEAEMA) and $N$-isopropylacrylamide (NIPAAm)/methacrylic acid (MAA) based on Pluronic, respectively. The chemical structure and molecular weight of the graft copolymers was characterized by $^1H$ NMR and gel permeation chromatography. The aqueous solution properties of graft copolymers were measured using a UV-visible spectrophotometer, contact angle and dynamic light scattering equipment with different temperature and pH conditions. The obtained graft copolymers showed a very sensitive phase transition in response to temperature and pH in aqueous media which suggested that the amine group of DEAEMA segment and carboxylic group of MAA had a great influence on the lower critical solution temperatures (LCST) in Polymer A and C, respectively. The graft copolymers can be utilized for drug delivery system and molecular switching applications where responses to temperature and pH changes are relevant.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.56-62
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• 2013

Poly (ethylene naphthalate) (PEN), which is likely to be widely used in various application due to good barrier properties, is manufactured by condensation polymerization of 2,6-dimethylnaphthalene dicarboxylate (2,6-NDC) or 2,6-naphthalene dicarboxylic acid (2,6-NDA) with ethylene glycol. In this study, an analytical method to determine monomers in food simulants, which might migrate from PEN food contact materials into food, was developed. The HPLC-UV method was validated for 2,6-NDC and 2,6-NDA. The obtained validation parameters were selectivity, sensitivity, linearity, precision and recovery. The simultaneous HPLC method was considered the be most effective analytical method to determine 2,6-NDC and 2,6-NDA in food simulants.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.588-596
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• 1996

The optimum conditions of the 1st and 2nd distillation had been investigated to obtaine a high quality monomeric MDI and fire reactive polymeric MDI by purification of crude MDI. Effect of additives on the monomeric MDI's color change, dimerization and the reactivity of polymeric MDI with standard polyol system has been tested. When the monomeric MDI yield is approximately 32%, 4,4'-MDI content is above 98% in the monomeric MDI at the 1st distillation. When the separation ratio of initial portion and residue percentage, reflux ratio are set at respectively, approximately 20wt%, 9wt%, above 2 in order to minimize the content of 2,4'-MDI in monomeric MDI, the freezing point of final distilled monomeric MDI is above $38.4^{\circ}C$. Since the monomeric MDI is inherently unstable in the room condition, monomeric MDI easily changes it's color and conducts self-polymerization reaction. To increase the stability of monomeric MDI, the composition of antioxidant, which is composed of phenolic 1st antioxidant, phosphorus 2nd antioxidant, UV absorbent and Hindered amine light stabilizer are used, and benzoyl chloride as antipolymerization agent test are that APHA color is less than 20, dimer content is remained less than 0.36wt% after 45 days storage of monomeric MDI.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.698-705
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• 1994

The basic medium oil modified alkyd resin was synthesized from linseed oil fatty acid(LOFA), phthalic anhydride(PAA), maleic anhydride(MA) and trimethylol propane(TMP) by condensation polymerization at $230^{\circ}C$. MA/TMPTA modified water-reducible alkyd resins were synthesized with TMPTA graft copolymerization onto the basic resin at $180^{\circ}C$. Acid value of the resin was controlled by the addition amount of MA and N,N-dimethylethanol amine(DMEA) was used as a neutralizing agent to prepare of the water-reducible alkyd resin. The effect of TMPTA on the graft copolymerization of the resin was studied by measuring molecular weight glass transition temperature(Tg), viscosity, graft efficiency, and gel contents of melanin cured film. Heat resistance, UV resistance and water resistance of cured film of MA/TMPTA modified resin was compared to those of TMA/TMPTA modified alkyd resin. The molecular weight, viscosity gel contents and graft efficiency of water reducible alkyd resin were increased according to the TMPTA graft copolymerization, but Tg was decreased. The viscosity was lower when the solid contents reached 40% than that of 30% content and also and also became lower with the extent of neutralization ratio, The heat resistance, UV resistance and water resistance of the MA/TMPTA modified alkyd resis were better than those of TMA/TMPTA modified alkyd resin but the storage stability of the TMA/TMPTA alkyd resis was better than that of MA/TMPTA modified alkyd resin.

• Journal of Ginseng Research
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• v.28 no.3
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• pp.157-164
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• 2004

The study was conducted to investigate the tissue and chemical characteristics of rusty root epidermal cells. In histological study, the rusty symptoms were frequently observed in the epidermis of ginseng root and to be yellow under microscopic observation. Disks of the epidermal cell tissue of the rusty root were usually 2 and 3 times greater in the number of cell layer and thickness of cell wall than the healthy root, respectively. The color degree of methanol extracts from the rusty root epidermis was 5.5 times higher than that of the healthy root. And the extracts of rust matter in the root epidermis were easily dissolved in polar solvents compared to nonpolar solvents. UV-absorption spectra of methanol extracts in various fractions of phenolics showed a maximum peak between 275∼280 nm. The crude lipids and phenolic compounds such as acid insoluble bound phenolics, acid insoluble esterified phenolics, acid insoluble condensed phenolics, insoluble bound phenolics and free phenolics were also more in the rusty root epidermis than in the healthy one. Fe content in the rusty root epidermis was 2.7 times higher than that of healthy one. It was presumed that the phenolic compounds(precursor of the rusty) in association with lipid and iron in the root epidermis might defence the root when ginseng root was depressed by the unfavorable conditions in soil and/or portions of a root system were subjected to anoxic conditions.

• Clean Technology
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• v.18 no.4
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• pp.366-372
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• 2012

Three acrylic copolymers containing tris(8-hydroxyquinoline) aluminum (AlQ3) pendant group (25 wt%), acrylateco-HEMA-$AlQ_3$ (25 wt%), were successfully synthesized by free radical polymerization from acrylates [methyl methacrylate (MMA), acrylonitrile (AN) or 2-hydroxyethyl methacrylate (HEMA)] with HEMA functionalized with AlQ3 pendant groups (HEMA-p-$AlQ_3$). The glass transition temperatures ($T_g$) of MMA-co-HEMA-p-$AlQ_3$ (copolymer 1), AN-co-HEMA-p-$AlQ_3$ (copolymer 2) and HEMA-co-HEMA-p-$AlQ_3$ (copolymer 3) were found to be 158, 150 and $126^{\circ}C$, respectively. They have good thermal stability: a very desirable feature for the stability of OLEDs. Their solubility, thermal properties, UV-visible absorption and photoluminescence behaviors were investigated. They were found to be soluble in various organic solvents such as tetrahydrofuran (THF), dimethylformamide (DMF), toluene and chloroform. It was also found that the UV-visible absorption and photoluminescence behaviors of these copolymers were similar to those of pristine $AlQ_3$. Green organic light-emitting diodes (OLEDs) have also been fabricated using these copolymers as light emission/electron transport components obtained easily by spin coating, and their current density voltage (J-V) curves were compared. The OLED device of the copolymer 3 had the lowest turn-on voltage of about 2 V compared to other copolymer types devices.

• Polymer(Korea)
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• v.35 no.6
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• pp.593-598
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• 2011

The IPA-co-HDO-co-(TPA/MA) copolymers for all-vanadium redox flow battery were synthesized by melt condensation polymerization using isophthalic acid(IPA), 1,6-hexandiol (HDO), terephthalic acid(TPA) and maleic anhydride(MA). The amination of chloromethylated IPA-co- HDO-co-(TPA/MA)(CIHTM) copolymer was carried out using trimethylamine, and the anion exchange membrane was also prepared by UV crosslinking reaction. The structure and thermal stability of IHTM copolymers were confirmed by FTIR, $^1H$ NMR, and TGA analysis. The anion membrane properties such as water uptake, ion exchange capacity, electric resistance and electrical conductivity, were measured by gravimetry, titration and LCR meter. The efficiency of the all-vanadium redox flow battery was analyzed. The ion exchange capacity, electric resistance and electrical conductivity were 1.10 meq/g, $1.98{\Omega}{\cdot}cm^2$, and 0.009 S/cm, respectively. The efficiency of charge-discharge, voltage, and energy for the allvanadium redox flow battery were 96.5, 74.6, 70.0%, respectively.

• Macromolecular Research
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• v.14 no.2
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• pp.173-178
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• 2006

Poly(3-(2-hydroxyethyl)thiophene) (P3HET) was synthesized using oxidative coupling polymerization that involved the protecting and deprotecting of hydroxyl groups but not the chlorine substitution or oxidative decomposition of the hydroxyl groups. The resulting P3HET exhibited good solubility in aprotic solvents, in contrast to the insoluble polymer product synthesized directly from the monomer, 3-(2-hydroxyethyl)thiophene (3HET). P3HET had low conductivity due to the strong hydrogen bonding of its hydroxyl groups. The ester-functionalized poly(3-(2-acetoxyethyl)thiophene) and poly(3-(4-pentylbenzoateethyl)thiophene) were also prepared with reasonably high molecular weights in order to examine how this functionalization modified the physical and chemical properties of P3HET. These polymers exhibited better solubility in common solvents and higher conductivity than P3HET. All these polymers exhibited bathochromic shifts of their film state absorption maxima with respect to those found in the UV-visible spectra of their solution phases. The extent of the bathochromic shift was found to vary with the lengths of the side chains of the ester-functionalized polymers.