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Park N.I.,University of Suwon | Park W.-S.,University of Suwon | Lee S.B.,EverChemTech Co. | Lee S.M.,EverChemTech Co. | Chung D.-W.,University of Suwon
Applied Chemistry for Engineering | Year: 2015

We conducted reduction reactions of graphene oxide (GO) using three selected reductants. The conductivity and solubility of three kinds of the reduced graphene oxides (RGOs) were examined based on the degree of reduction. When the ethylene glycol (EG) was used as a reductant, the reduction reaction did not sufficiently progress and as a result the conductivity of RGOs was observed to be relatively low. For RGOs made by hydrazine (HZ) and thiourea dioxide (TU), we observed no significant differences in the degree of the reduction, conductivity and dispersity in water. However, RGO prepared by TU showed an exceptionally good solubility in N-methylpyrrolidone, and the solution was stable for more than 4 months. © 2015, Korean Society of Industrial Engineering Chemistry. All rights reserved.


Choi J.W.,EverChemTech Co. | Lee S.B.,EverChemTech Co. | Lee S.M.,EverChemTech Co. | Park W.-S.,University of Suwon | Chung D.-W.,University of Suwon
Applied Chemistry for Engineering | Year: 2015

We prepared films by a bar-coating of various graphene oxide (GO) pastes by varying pH with amine compounds. The thermal treatment of films at 150 ℃ and measurement of surface resistances exhibited that the pH variation does not significantly affect the surface resistance. We, however, found that the addition of amines reduced the surface resistance by approximately 10 times and N, N-dimethylethanolamine (DMEA) showed the most significant effect among all amines investigated. XPS studies demonstrated that the addition of DMEA accelerated the reduction reaction of GO, and finally enhanced the electrical properties of GO films. © 2015, Korean Society of Industrial Engineering Chemistry. All right reserved.


Choi J.H.,University of Suwon | Park W.-S.,University of Suwon | Lee S.M.,EverChemTech Co. | Chung D.-W.,University of Suwon
Applied Chemistry for Engineering | Year: 2016

In order to investigate the thermal stability of electro-conductive poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT/PSS), we have prepared films by casting PEDOT/PSS aqueous solution without using a binding material and measured surface resistances of the films while annealing at 200 ℃. Electrical properties of films were improved by annealing, and the maximum conductivity (540 S⋅m-1) after annealing for 2 hrs was found to be approximately 3 times higher than that (180 S⋅m-1) of the original film. The conductivities, however, dramatically decreased with an increase in annealing time and dissipated after 24 hrs of annealing. On the other hand, PEDOT/PSS films hybridized with graphene oxide (GO) displayed a salient improvement in conductivity by annealing, which was measured to be around 600 S⋅m-1 even after 30 hrs of annealing at 200 ℃. We tentatively conclude that hybridization with GO enhances the thermal stability of PEDOT/PSS. © 2016 The Korean Society of Industrial and Engineering Chemistry. All rights reserved.


Kim M.C.,University of Suwon | Park M.U.,University of Suwon | Park N.I.,University of Suwon | Lee S.B.,EverChemTech Co. | And 4 more authors.
Applied Chemistry for Engineering | Year: 2016

In the presence of poly(4-styrene sulfonate) (PSS) and excess amount of graphene oxide (GO), we conducted in-situ polymerization of 3,4-ethylenedioxythiophene (EDOT) without an oxidant. XPS and IR spectroscopies of the product (GO-P) showed that PEDOT/PSS was successfully synthesized by oxidative polymerization of EDOT and hybridized with GO. GO-P displayed a stable aqueous suspension, however, the high content (42%) of GO in GO-P diminished electrical conductivity down to 15 S⋅m-1. Annealing of GO-P films at 200 °C for 8 hr induced partial reduction of GO and finally enhanced electrical conductivity up to 212 S⋅m-1. © 2016, The Korean Society of Industrial and Engineering Chemistry. All Rights Reserved.


Kim J.Y.,University of Suwon | Yang H.J.,University of Suwon | Pak N.Y.,EverChemTech Co. | Choi Y.J.,EverChemTech Co. | And 2 more authors.
Applied Chemistry for Engineering | Year: 2013

We conducted investigation on polymeric binders for anti-static coating agent which can maintain stability under the high-voltaic condition. Various polyesters composed of polyethylene glycol (PEG) and polypropylene glycol (PPG) were synthesized and studied in term of the variation in the surface resistance of the film made from coating solution composed of a conductive polymer and these polyesters as a binder. We found that the surface resistance displayed 107~108 Ω/□ regardless of chemical composition of binders under the potential of 10 V. Whereas, the surface resistance surged to higher than 2 × 1010 Ω/□ when 1000 V was applied, rendering it improper for anti-static purpose. When 1,4 butanediol (BD) was incorporated into polyesters ([PEG]/[PPG]/[BD] = 25.0/67.5/7.5), the surface resistance showed 2.8 × 109 Ω/□ under 1000 V, acceptable for anti-static application. These observations may indicate that the hydrophobic nature of BD makes a significant contribution to the surface resistance at a high positive potential.


Lee S.B.,EverChemTech Co. | Lee S.M.,EverChemTech Co. | Park N.I.,University of Suwon | Lee S.,University of Suwon | Chung D.-W.,University of Suwon
Synthetic Metals | Year: 2015

We report here a synthetic route to producing electro-conductive graphene/polymer nanocomposite (GP) based on poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and partially reduced graphene oxide (pRGO). GP was prepared by in situ oxidative polymerization of EDOT using PSS as a template in the presence of graphene oxide (GO). During the polymerization, GO was partially reduced, while the resulting nanocomposite (GP) displayed a stable aqueous suspension. Compared with a simple mixture of GO and pre-prepared PEDOT:PSS, GP showed an enhanced electrical conductivity of 9.2 S cm-1. © 2015 Elsevier B.V.


Park N.I.,Suwon UniversityGyeonggi do | Lee S.B.,EverChemTech Co. | Lee S.M.,EverChemTech Co. | Chung D.-W.,Suwon UniversityGyeonggi do
Applied Chemistry for Engineering | Year: 2014

We conducted investigation on the hybridization of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT: PSS) with graphene derivative (G-PSS), which has been prepared by wrapping reduced graphene oxide (RGO) with PSS. In situ polymerization of PEDOT/PSS in the presence of G-PSS afforded the PEDOT/PSS and graphene hybrid (GP). The analysis of XPS, IR and Raman spectroscopies for GP showed that PEDOT/PSS was successfully synthesized and hybridized with graphene. Compared to the G-PSS, GP showed an enhanced electrical conductivity of 4.46 × 102 S/m with a good wter-dispersity. © 2014 The Korean Society of Industrial and Engineering Chemistry. All rights reserved.


Trademark
Everchemtech Co. | Date: 2015-10-09

Chemical compound for conducting polymers; Enzymes for industrial purposes; Damp-proofing chemicals, except paints, for masonry; Chemical preparations for analyses in laboratories, other than for medical purposes; Ferments for non-medical and non-veterinary chemical purposes; Industrial chemicals; Chemical agents for the anti-static protective coating of electronic materials; Chemical agents for the anti-static coating of light-diffusing film; Chemical agents for use in antistatic coatings; Chemical agents for the antistatic coating of electronic component element transport module trays; Chemicals for metal cleaning; Chemicals for industrial purposes, namely, chemicals for the treatment of metal surfaces; Industrial chemicals for electronics/optics cleaning; Chemicals for industrial purposes; Unprocessed plastics; Unprocessed synthetic resins; Unprocessed polyethylene resins; Unprocessed polyvinyl chloride resins; Unprocessed polyester resins; Adhesives for industrial purposes.

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