• Bulletin of the Korean Chemical Society
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• v.1 no.4
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• pp.138-143
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• 1980

Hydrogel membranes were prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (VP) in the presence of the solvent and the crosslinker tetraethyleneglycol dimethacrylate (TEGDMA). By changing the monomer composition and the crosslinker content, different membranes were synthesized. Using these membranes, relative permeabilities and distribution coefficients for amides including urea were measured. The water contents in membrane were also measured. On the basis of solute-membrane matrix interaction, the results were interpreted.

• Clean Technology
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• v.12 no.4
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• pp.191-197
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• 2006

Polymerization in supercritical carbon dioxide has been getting attention since it is easier to separate the remaining reactants from product polymer and since it is a cleaner process that produces neither wastewater nor air pollutants, compared to the conventional polymerization processes. In this study, poly(vinyl acetate) (PVAc) that is necessary in producing poly(vinyl alcohol) (PVA) with a lot of industrial applications was manufactured in the presence of supercritical carbon dioxide for the second time in the world. A poly(dimethylsiloxane)(PDMS)-derivative surfactant and three initiators were employed in the polymerization of vinyl acetate (VAc) at 338.15 K and 34.5 MPa. Investigation was carried out to find out the effect of the amounts and types of initiators and surfactants as well as the effect of reaction time on the yield and the molecular weight of PVAc. The weight average molecular weight (Mw) of PVAc was in the range of 60,000 ~ 140,000 g/mol, and the number average molecular weight was in the range of 30,000 ~ 70,000 g/mol. The yield of PVAc was spread over 10 ~ 80%, based on the amount of VAc monomer.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.625-629
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• 2011

A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.

• Safety and Health at Work
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• v.11 no.2
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• pp.215-221
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• 2020

Background: The aim of this study is to illustrate the historical role of the International Commission on Occupational Health (ICOH) congresses as an arena where national and international occupational medicine can dialogue and as the first example of scientific transferability of the research and prevention results that have had such an impact on global public health. Methods: We used the ICOH Heritage Repository, in which ICOH congress proceedings (from the first congress in Milan in 1906 to the last congress, held in Dublin in 2018), are organised in an orderly way, updated and easily accessible according to open access logic. Results: We describe studies by three physicians who submitted significant scientific work to ICOH congresses, one on the battle against ancylostomiasis (Volante, 1906), the second (Quarelli, 1928) on carbon disulphide poisoning, and the third (Viola, 1969) on the carcinogenicity of vinyl chloride monomer. Priority is given to Italian cases, on account of the authors' obvious familiarity with the issues. Conclusion: The visibility offered in ICOH conferences and their published proceedings has boosted the international spread of their findings, contributing to the scientific transferability of the research results and influencing the development of policies and prevention interventions that have had a great impact on global public health.

• Polymer(Korea)
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• v.28 no.2
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• pp.135-142
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• 2004

Poly(vinyl acetate) (PVAc) prepared by emulsion polymerization has broad applications for additives such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has a disadvantage that surfactant and ionic initiator degrade properties of the product polymer, poly(vinyl acetate-co-butyl acrylate) (VVc-BA) was synthesized using potassium persulfate as catalyst and poly(vinyl alcohol) (PVA) as protective colloid to prevent the degradation. The copolymer latex product was internally plasticized and has enhanced colloid stability, adhesion, tensile strength and elongation. During VAc-BA emulsion polymerization, no coagulation and complete conversion occur with the reactant mixture of 0.7wt% potassium persulfate, 15wt% poly(vinyl alcohol) (PVA-217), and the balanced monomer that the weight ratio of vinyl acetate to butyl acrylate is 19. As the concentrations of PVA increase, the copolymerization becomes faster and polymer particles are more stable, resulting in enhanced mechanical stability of the VAc-BA copolymer. However, the size of the polymer particles decreases with increasing PVA contents. Properties of the VAc-BA copolymer, such as minimum film formation temperature, glass transition temperature, surface morphology, molecular weight and molecular weight distribution, tensile strength and elongation, were characterized using differential scanning calorimeter, transmission electron microscope and other instruments.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.621-626
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• 2010

Anion exchange membranes can be used for reverse electrodialysis for electric energy generation, and capacitive deionization for water purification, as well as electrodialysis for desalination. In this study, anion exchange membranes of poly((vinylbenzyl) trimethylammonium chloride-2-hydroxyethyl methacrylate)/poly(vinyl alcohol) were prepared through the polymerization of (vinylbenzyl)trimethylammonium chloride and 2-hydroxyethyl methacrylate in aqueous poly(vinyl alcohol) solutions, esterification with glutaric acid, and cross-linking reaction with glutaraldehyde. We investigated electrochemical properties for the anion exchange membranes prepared according to experimental conditions. Ion exchange capacity and electrical resistance for the membranes were changed with a variation in the monomer ratio in polymerization. Water uptake and conductivity for the membranes decreased with an increase in the content of glutaric acid in esterification. The change in the time of crosslinking reaction with the formed film and glutaraldehyde affected electrochemical properties such as water uptake, conductivity, or transport number for the membranes. Chronopotentiometry and limiting current density for the anion exchange membranes prepared were measured.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.299-308
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• 1976

Cerium (Ⅳ) ion-initiated graft copolymerizations of acrylamide and of acrylonitirile to silk fibroins were investigated. When acrylamide was used, the change in ceric ammonium nitrate concentration exhibited a maximum in degree of grafting at 0.01 M. Also observed was that the change in acetic acid content in reaction media gave a maximum in degree of grafting at 7% acetic acid in water. Degree of grafting was increased generally with increase in acrylamide concentration reaction time and reaction temperature. When acrylonitrile monomer was used for grafting,different results were obtained. Addition of nitric acid was more effective in enhancing the degree of grafting than the addition of acetic acid.Generally the grafting of acrylonitrile to silk fibroins was less efficient than the grafting of acrylamide. The portion of grafted silk fibroins insoluble in Lowe's reagent exhibited the IR absorption bands characteristics to both vinyl polymers and silk fibroins, indicating the grafting of vinyl monomers to silk fibroins. To examine the molecular weight of graft vinyl polymer, a sample of grafted silk was hydrolyzed by 10% sodium hydroxide. Viscosity measurements indicated that the molecular weight of the graft polymer was in the range of 105.

• Macromolecular Research
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• v.11 no.2
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• pp.115-121
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• 2003

In this research, the in vitro anti-thrombogenecity of artificial materials was evaluated using hydrophilic/hydrophobic copolymers containing oiligosaccharide as hydrophilic moiety and phospholipid as hydrophobic moiety respectively. N-(p-vinylbenzyl)-[O-$\alpha$-D-glucopyranosyl-(1longrightarrow4)]$_{n-1}$-D-glucoamide(VM7A) was (VM7 A) was adopted as hydrophilic oligosaccharide and 2-acryloxybutyl-2-(triethylammonium)ethyl phosphoric acid (HBA-choline) was adopted as hydrophobic phospholipid. Copolymers having various monomer feeding molar ratios were synthesized through radical polymerization. The synthesized copolymers were identified using FT-IR, $^1$H-NMR, XPS, and DSC. The surface energy of the copolymers were evaluated by dynamic contact angle (DCA) method and checked different roles of VM7A as hydrophilic moiety and HBA-choline as hydrophobic moiety on surface. The surface morphological differences between hydrated and unhydrated surfaces of copolymers were observed and evaluated using Am. The platelets were separated from canine whole blood by centrifugation and adopted to the anti-thromobogenecity test of the copolymers. From the results, we find out that as VM7A ratio increases, so did anti-thrombogenecity. Such results show the possibility of using these copolymers as blood compatible materials in living body.y.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.37-43
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• 2013

This study was focused on applying a new paper coating binder, vinyl acetate-ethylene(VAE) emulsion, with SB-latex and acrylic emulsion for paper coating application. VAE emulsion has a low monomer cost and is non-toxic chemical than conventional adhesive for paper coating such as styrene-butadiene latex( SB-latex) and acrylic emulsion. We conducted double coating in order to test VAE emulsion, which was applied on top surface only. The results showed that optical properties of the coated paper with VAE were similar with the SB-latex binders. In case of bonding strength, dry-pick of the coated paper with VAE showed almost same with other binders while wet-pick of the coated paper with VAE had a little bit lower strength than that with SB-latex.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05a
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• pp.9-15
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• 2004

The copolymerization of HEMA with different hydrophilic and hydrophobic co-monomers allows for the manipulation of their intrinsic properties. 2-Hydroxyethylmethacrylate (HEMA)-based hydrogels thus are of great interest due to their outstanding physico-mechanical properties and chemical stability. The idea to use HEMA in order to create thermo-sensitive polymers was based on our assumption that thermal-sensitivity comes from a suitable hydrophilic-hydrophobic balance of macromolecules. In this work we have chosen N-vinyl pyrrolidone as a hydrophilic co-monomer with the relatively hydrophobic HEMA due to its good polymerizing properties as well as its non-toxicity in a polymer state and deserved recognition as a biocompatible material. As a result, copolymerization of NVP and HEMA was successful in obtaining new types of thermo-sensitive polymers composed of hydrophilic and hydrophobic monomers.