• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.669-675
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• 2008

Carbon black has been widely used in composites, tonor resin, and ink materials. Since carbon black readily agglomerates, it is important to disperse carbon black in real applications. Aiming to improve dispersion stability, carbon black was chemically oxidized to possess hydroxyl groups using a phase transfer catalyst at room temperature. The modified carbon black (CB-OH) was grafted by a silane coupling agent, p-methylacryloxypropyltrimethoxysilane, to carry teminal vinyl groups. The modified carbon black was subsequently used in miniemulsion polymerization to achieve encapsulted core-shell structure. Finally, well-encapsulated carbon black by polymer was obtained in the size range of 100-500 nm. Throughout the polymerization, the effects of surface modification, types of monomers, initiators, and emulsifiers were investigated.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.449-452
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• 2012

A polyaniline-gold composite was prepared via the polymerization of aniline hydrochloride with or without water-soluble graphite oxide using auric acid as an oxidant. The reaction products were characterized using Xray photoelectron spectroscopy. The thermal stability and embedded crystallinity of the composites were also investigated using thermogravimetric and X-ray diffraction analyses. The electrical properties of the composites were examined using cyclic voltammetric measurements at room temperature and temperature-dependent DC conductivity within 300-500 K. Compared to pure graphene oxide and polyaniline-gold composite, the polyaniline-gold-graphene composite exhibited higher crystallinity and thermal stability, and higher current density response under equivalent conditions.

• Journal of the Korean Ceramic Society
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• v.31 no.6
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• pp.660-670
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• 1994

Transparent, crack-free dried gel monoliths with a composition of LiZr1.5Si2P2O12.5 have been synthesized by the low temperature polymerization of the Sol-Gel technique using metal alkoxides as starting materials. After initial reaction (20~40 min), each metal alkoxide closely paralleled each other during the hydrolysis reactions. The safe drying conditions of gels with no creaks the control of the shrinkage rate. The gels converted into the glass by heat treatment at 75$0^{\circ}C$. FTIR data indicated that the gels were phase separated into silicarich and phosphate-rich regions with the lithium. XRD results showed the formation of crystalline LiH2PO4. The gels dried at 15$0^{\circ}C$ or fired at 75$0^{\circ}C$ contained the residual water. The high ionic conductivity at room temperature for these gels was attributed to the motion of protons.

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.383-387
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• 2014

Electrically conductive polypyrrole-polyvinylpyrrolidone (PPy-PVP) nanofiber mats with a core-shell structure have been successfully fabricated by a two-step process: the formation of FeCl3-containing PVP nanofiber mat by electrospinning, and the vapor-phase polymerization (VPP) of pyrrole monomer on the mat in a sealed chamber at room temperature. Surface morphology and chemical composition of the PPy-PVP mat were characterized by SEM, EDX and FTIR analyses. The as-prepared nonwoven mat was composed of PPy-PVP nanofibers with an average diameter of 300 nm. The sheet conductivity of the nanofiber mat was measured to be approximately 0.01 S/cm by a four-point probe. We have also investigated gas-sensing properties of PPy-PVP nanofiber mat upon exposure to methanol vapor. The PPy-PVP nanofiber sensors were observed to have excellent methanol-sensing performance. The nanofiber-based core-shell nanostructure could give an opportunity to fabricate a highly sensitive and fast response sensor due to its high surfaceto-volume ratio.

• Textile Coloration and Finishing
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• v.24 no.2
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• pp.97-105
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• 2012

Compared with conventional adsorption-based coloration, the photoreactions of dyes such as photo-copolymerization and photo-crosslinking under UV irradiation can be employed for the coloration of textiles, which can be carried out without salt addition at room temperature. C.I. Reactive Black 5, a homo-bifunctional reactive dye containing two sulfatoethylsulfone groups, is used as a photo-reactive dye for wool fibers. Upon UV irradiation, the photo-reactive dye was grafted onto wool fabrics without photoinitiators. Since the disulfide bonds in the cystine residues of wool can be easily photodecomposed to active thiyl radicals which initiate the polymerization, the dye can be polymerized to an oligomeric dye of a degree of polymerization of 12 or more. The grafted fabrics reached a grafting yield of 2.3% o.w.f. and a color yield (K/S) of 18.2 by the photografting of an aqueous dye concentration of 9% using a UV energy of 25J/$cm^2$. Furthermore, the photochemically dyed wool fabric showed higher colorfastness properties to light, laundering and rubbing comparable to conventional reactive dyeing.

• Korean Journal of Materials Research
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• v.13 no.12
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• pp.796-800
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• 2003

The polypyrrole prepared with pyrrole monomer, APS and DBSA was synthesized by chemical Polymerization at $V^{\circ}C$ under atmosphere conditions. After dissolving polypyrrole powder to the chloroform including DBSA, polypyrrole film was prepared on the alumina substrate with an interdigitated electrode by using the dip-coating method. This film was soaked in methanol solvent for 1 h at room temperature and heated to $70^{\circ}C$ for 4 h in $N_2$. Initial resistance was increased with the increasing humidity and decreasing temperature. The sensitivity was increased with lower humidity and decreasing temperature. The best linearity was achieved at $25^{\circ}C$ and low humidity of 0%.

• Journal of Sericultural and Entomological Science
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• v.41 no.3
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• pp.185-195
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• 1999

This study was carried out to improve the skin care property of the polyester fabric by finishing with sericin. It was known that skin care function, anti-oxidation, anti-tyrosinase activity and anti-elastase activity can be achieved from sericin finish. But, the moisture regain of the finished fabric was measured simply, because the major cause of the discomfort from polyester fabric has been anounced to be wetness. The effects of various treatment conditions on the properties of the finished fabric were measured, and obtained results were as follows: 1. The moisture regain at 40$^{\circ}C$ 90% RH were increased with the sericin uptake increasing. while it was not significant for the effects on the moisture regain depending on the treatment conditions like the degree of polymerization and treatment concentration of the binder. The moisture release of the fabric having sericin uptake 1%, 2% was faster than non treated fabric. The change of the moisture regain of the finished fabric from 40$^{\circ}C$ 90% RH to room temperature was 4∼5 times higher than that of knitted cotton fabric. 2. The frictional static charge was decreased with the degree of polymerization of the binder increasing. While the sericin uptake and treatment concentration of the binder were not significant. 3. The whiteness value of the fabric was slightly decreased by finishing with sericin and binder. In that cases, W values of the finished fabrics were above 90 while that depending on the degree of polymerization of the binder was not significant. 4. The major cause of the yellowness of the finished fabric was proved to be catalyst. The yellowness of the finished fabric with sulfur containing catalyst was lower than that with amine group containing catalyst. 5. The effects of the treatment concentrations of the cross-linking agent, catalyst and drying time on the wash durability were not significant.

• Polymer(Korea)
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• v.28 no.3
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• pp.211-217
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• 2004

The sol to gel transition of aqueous solution of block copolymers consisting of methoxy poly (ethylene glycol) (MPEG) and biodegradable polyesters such as $\varepsilon$-caprolactone and L-lactide was investigated as a function of temperature. MPEG-PCL was prepared by ring opening polymerization of $\varepsilon$-caprolactone in the presence of HClㆍEt$_2$O as monomer activator at room temperature. Also, MPEG-PLLA was prepared by ring opening polymerization of L-lactide in the presence of stannous octoate at 115$^{\circ}C$. The properties of block copolymers were investigated by $^1$H-NMR, IR, and GPC as well as the observation of thermo sensitive phase transition in aqueous solution. As the hydrophobic block length increased, the sol to gel transition temperature increased and curve of that steepen to lower concentration. To confirm the gel formation at body temperature, we observed the formation of gel in the mice body after injection of 20 wt% aqueous solution of each block copolymer. After surging, we investigated the gelation in mice. The results obtained in this study confirmed the feasibility as biomaterials of injectable implantation for controlled release of drug and protein delivery.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.36-43
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• 2016

Hydrosilylation reactions of 2.4.6.8-tetrahydro-2.4.6.8-tetramethylcyclotetrasiloxane with allyl butyrate catalyzed by Karstedt's, $H_2PtCl_6$ and Pt/C catalyst were studied and 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane was obtained. The reaction order, activation energies and rate constants were determined. Ringopening polymerization of 2.4.6.8-tetra (propyl butyrate)-2.4.6.8-tetramethylcyclotetrasiloxane in the presence of $CaF_2$, LiF, KF and anhydrous potassium hydroxide in $60-70^{\circ}C$ temperature range was carried out and methylsiloxane oligomers with regular arrangement of propyl butyrate pendant groups were obtained. The synthesized products were studied by FTIR and NMR spectroscopy. The polysiloxanes were characterized by wide-angle X-ray, gel-permeation chromatography and DSC analyses. Via sol-gel processes of oligomers doped with lithium trifluoromethylsulfonate or lithium bis (trifluoromethylsulfonyl)imide, solid polymer electrolyte membranes were obtained. The dependences of ionic conductivity of obtained polyelectrolytes on temperature and salt concentration were investigated, and it was shown that electric conductivity of the polymer electrolyte membranes at room temperature changed in the range $3.5{\times}10^{-4}{\sim}6.4{\times}10^{-7}S/cm$.

• Polymer(Korea)
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• v.25 no.2
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• pp.263-269
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• 2001

MAPTAC-MMT was prepared by exchanging the mineral cation (sodium montmorillonite) with 3-(methacryloyl amino) propyltrimethyl ammonium chloride, thus rendering the mineral organophilic and forming polymerizable moieties directly bonded to the surface of montmorillonite (MMT). Thermoresponsive nanocomposites (PNIPAM-MMT) were synthesized by polymerization of N-isopropyl acrylamide in an aqueous suspension of MAPTAC-MMT at room temperature. Thermoresponsive nanocomposites exhibited a low critical solution temperature (LCST) similar to unmodified poly(N-isopropyl acrylamide) (PNIPAM). The LCST of thermoresponsive nanocomposites decreased in proportion to the amount of MAPTAC-MMT. TGA results showed that the thermal stability of thermoresponsive nanocomposites was improved compared to PNIPAM itself the thermoresponsive polymer.