• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.411-415
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• 2020

In this article, the preparation of hydrogels containing conducting polymer@lignin hybrids and their application to sensing materials were demonstrated using diverse techniques. A conducting polymer, polypyrrole (PPy) was polymerized on the surface of lignin and successful formation was analyzed with Fourier-transform infrared spectroscopy and scanning electron microscopy. Subsequently, PPy@lignin hybrids were mixed with a hydrogel matrix to obtain a conductive hydrogel. The feasibility of using the hydrogel as a sensing material was shown by obtaining reasonable sensing signals using various electrical measurements when adding solvents and solutions to the sensor system. The significance of sensor signals was confirmed with complementary experiments. This study shows that the hydrogel containing the PPy@lignin could be used for sensor applications.

• Journal of Electrochemical Science and Technology
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• v.9 no.3
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• pp.220-228
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• 2018

This study introduced a carbon-free electrode for $Li-O_2$ cells with the aim of suppressing the side reactions activated by carbon material. Micro-particles of poly(3,4-ethylenedioxythiophene) (PEDOT), a conducting polymer, were used as the base material for the air electrode of $Li-O_2$cells. The PEDOT micro-particles were treated with $H_2SO_4$ to improve their electronic conductivity, and LiBr and CsBr were used as the redox mediators to facilitate the dissociation of there action products in the electrode and reduce the over-potential of the $Li-O_2$ cells. The capacity of the electrode employing PEDOT micro-particles was significantly enhanced via $H_2SO_4$ treatment, which is attributed to the increased electronic conductivity. The considerable capacity enhancement and relatively low over-potential of the electrode employing $H_2SO_4$-treated PEDOT micro-particles indicate that the treated PEDOT micro-particles can act as reaction sites and provide storage space for the reaction products. The cyclic performance of the electrode employing $H_2SO_4$-treated PEDOT micro-particles was superior to that of a carbon electrode. The results of the Fourier-transform infrared spectroscopic analysis showed that the accumulation of residual reaction products during cycling was significantly reduced by introducing the carbon-free electrode based on $H_2SO_4$-treated PEDOT micro-particles, compared with that of the carbon electrode. The cycle life was improved owing to the effect of the redox mediators. The refore, the use of the carbon -free electrode combined with redox mediators could realize excellent cyclic performance and low over-potential simultaneously.

• Macromolecular Research
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• v.14 no.4
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• pp.466-472
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• 2006

The kinetic behavior of emulsion polymerizations of styrene in the presence of sulfonated N-hydroxy ethyl aniline (SHEA) was investigated with two initiators: 2,2'-azobisisobutyronitrile (AIBN) and potassium persulfate (KPS). SHEA was synthesized using a stepwise polyurethane reaction method from 3-hydroxy-1-propane sulfonic acid sodium salt, isophorone diisocyanate (IPDI), and N-(2-hydroxyethyl) aniline. Stable core-shell poly(styrene/sulfonated N-hydroxy ethyl aniline, St/SHEA) latex particles were successfully prepared by using an appropriate amount of AIBN, in which SHEA plays the role of 'surfmer', i.e., acting as both a surfactant in the emulsion polymerization and a monomer in the chemical oxidative polymerization. The kinetic behavior was dissimilar to that of typical emulsion polymerization systems. A long inhibition period and low rate of polymerization were observed due to radical loss by the oxidative polymerization of SHEA. It was concluded, due to the low water-solubility of AIBN and retardation reaction by SHEA, that the initial loci of polymerization were monomer droplets. However, growing polymer particles as polymerization loci became predominant as polymerization proceeded. It was suggested that AIBN was more effective than KPS in the preparation of the core-shell type poly(St/SHEA) latex particles. With KPS, no substantial polymerization was observed in any of the samples.

• Polymer(Korea)
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• v.38 no.2
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• pp.250-256
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• 2014

Polypropylene (PP) composites containing conductive multi-walled carbon nanotube (MWNT) and stainless steel short fiber (SSF) were manufactured using a twin screw extruder and characterized their surface resistivity and mechanical properties in this work. Surface resistivity measurements showed that the percolation threshold appeared at a lower MWNT loading when a small amount of SSF was added to PP/MWNT composites. Tensile modulus and strength of the composites increased but elongation-at-break decreased greatly compared to pure PP. Also, the effects of MWNT and SSF on storage modulus and tan ${\delta}$ from dynamic mechanical analysis for the composites were examined, and the morphologies of fractured surface and the fillers were observed using a scanning electron microscope.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.4
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• pp.169-174
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• 2014

The effect of varying amounts of graphite and $TiB_2$ on the electrical conductivity of composite bipolar plates was systematically studied. In this study, Titanium diboride ($TiB_2$) which has a high electrical conductivity, was selected as a filler and a additive material instead of conventional graphite. For proper distribution of the filler and matrix materials, ball milling using alumina balls was conducted for 1h, and then the hot press method was applied for the preparation of composite samples. The results showed a rapid increase in the electrical conductivity of composite bipolar plates at the critical filler content. However, $TiB_2$ and graphite composite bipolar plates showed similar increases in the electrical conductivity even though $TiB_2$ has a higher electrical conductivity than graphite. In addition, it was also found that a small addition of $TiB_2$ to graphite filler could be very effective for increasing the electrical conductivity and flexural strength of the composite bipolar plate.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.539-546
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• 2006

A study on the polymerization of polyethylenedioxythiophene (PEDOT) and the carbonization process of a separator was carred out in order to apply conductive polymer PEDOT to the winding typed aluminum condenser as a solid electrolyte and a negative electrode. PEDOT was polymerized with ethylenedioxythiophene (EDOT) as a monomer and ferric-p-toluenesulfonate as an oxidizing agent. The separator of condenser element was carbonized to control its fibrous tissue for the purpose of making it easy to impregnate the PEDOT solution into the microporous etched pit of aluminum foil by preventing separator from concentrating the PEDOT solution on itself. The characteristics of condenser such as capacitance, dissipation factor, equivalent series resistance, and thermal resistance depended on a carbonization temperature and a carbonization time. It was found that a thickness and a density of the used separator were major parameters of carbonization process and the characteristics of condenser were affected by these parameters.

• Polymer(Korea)
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• v.36 no.5
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• pp.599-605
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• 2012

The physicochemical properties such as surface hardness, solvent mechanical wear resistance, and resistance to scratch properties of poly(3,4-ethylenedioxythiophene) (PEDOT) thin film prepared by vapor phase polymerization (VPP) was effectively improved by post-treatment of various metal alkoxide sol solutions. Metal oxide layer derived from sol-gel process of metal alkoxide was generated on the PEDOT thin film layer by VPP, resulting in improving mechanical properties of the conductive thin films without any deterioration of their original surface resistance. Several kinds of silicone and titanium alkoxide derivatives with various functional groups were used as metal alkoxide sol sources. Among them, PEDOT-metal oxide composite thin film derived tetraethyl orthosilicate showed the best performance in the terms of surface resistance, transmittance, and various physicochemical properties. The effect of metal alkoxide content in washing solution, oxidant content and drying temperature have been investigated in order to optimize the various properties of PEDOT-metal oxide composite thin film.

• Membrane Journal
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• v.6 no.4
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• pp.258-264
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• 1996

Polyanilines were prepared by the oxidative polymerization in the presence of ammonium persulfate as an oxidant. After dehydration, a doping was carried out by mixing the polymer solution with dopants and immersing into aqueous dopant solutions. Using various riopants, the d-spacing of polyanilines can be controlled from $3.72{\AA}$ to $4.844{\AA}$. The d-spacing of polyanilines with polymeric or bulky dopants was larger than that of as-cast polyaniline. The characterization of the physical properties were confirmed by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dielectric analyzer (DEA) etc. Annealed polyaniline membrane exhibited the oxygen permeability of 0.072 barrer and the oxygen selectivity to nitrogen was 6.87. For the gas separation of polyanilines with polymeric or bulky riopants, the permeability increased while the selectivity detereased. Permeability can be readily controlled by the use of bulky dopants.

• Polymer(Korea)
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• v.37 no.6
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• pp.722-729
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• 2013

In order to enhance the thermal conductivity of poly(dimethyl siloxane) (PDMS), boron nitride (BN) and carbon nanotubes (CNTs) were incorporated as the thermally conductive fillers. The amount of BN was increased from 0 to 100 phr (parts per hundred rubber) and the amount of CNTs was increased from 0 to 4 phr at a fixed amount of the boron nitride (100 phr). The thermal conductivity of the composites increased with an increasing concentration of BN, but the incorporation of CNTs had only a slight effect on the enhancement of thermal conductivity. Unexpectedly, the thermal degradation of the composites was accelerated by the addition of CNTs in 100 phr BN filled PDMS. Activation energy for thermal decomposition of the composites was calculated using the Horowitz-Metzger method. The curing behavior, electrical resistivity, and mechanical properties of PDMS filled with BN and CNTs were investigated.

• Composites Research
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• v.37 no.3
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• pp.197-203
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• 2024

Mechanical, electrical and thermal properties of polymer composites can be improved simultaneously by incorporating carbon fibers (CFs), which are beneficial for improving the mechanical properties, and multi-walled carbon nanotubes (MWCNTs), which are advantageous for improving the conductive properties. In this study, MWCNTs were incorporated into carbon long fiber thermoplastic (CLFT), which has excellent mass production processability and excellent mechanical properties, to control electrical and thermal properties. The mechanical and electrical properties of the prepared composites were most significantly influenced by the amount of filler incorporated. On the other hand, the thermal properties were improved due to the formation of a filler network interconnected by the incorporation of MWCNTs. By adjusting the filler amount, filler composition, and filler network structure of MWCNT-incorporated CLFT, the mechanical, electrical, and thermal properties could be controlled.