• Elastomers and Composites
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• v.40 no.1
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• pp.53-58
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• 2005

Carbon tetrachloride is very reactive chain transfer agent due to the resonance stability of the trichlorocarbon radicals after breaking of C-Cl bond. Effect of benzylic radical comparing to trichlorocarbon radicals in the chain tranrfer reactions was investigated. From the structural point of view, cumyl chloride is a good candidate because it has the C-Cl bond with benzylic radicals after displacement of C-Ci bond. The reactivity of free radical polymerization of styrene in the presence of cumyl chloride was compared with that of carbon tetrachloride by calculating chain transfer constants. Results show that the cumyl chloride acts as a stronger chain transfer agent than carbon tetrachloride. The calculated chain transfer constant of cumyl chloride shows higher value (0.0463) than that of carbon tetrachloride (0.0011) in the styrene polymerization. High reactivity of cumyl chloride comparing to that of carbon tetrachloride is probably due to the higher resonance stability or benzylic radical than that or trichlorocarbon radicals after breaking of C-Cl bond. Monte Carlo simulation method is applied for characterizing the validity of kinetic constants according to the ratio of chain transfer agent to monomer.

• Polymer(Korea)
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• v.36 no.3
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• pp.351-356
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• 2012

Acryl binder is a representative organic additive for the manufacture of the display electronic equipment. Acryl binder is usually synthesized by radical copolymerization. Glycidyl methacrylate (GMA), methyl methacrylate (MMA), and methacrylic acid (MAA) were used in this copolymerization of acryl binder. In this study the silane type mercaptane compound was used as a chain transfer agent (CTA) to enhance the adhesion property of the acrylic binder. The CTA used in this experiment was (3-mercaptopropyl) trimethoxysilane (MPTMS). Molecular weight of the copolymer, thickness of the coating, transmittance, and adhesion property were measured. The molecular weight was controlled and the adhesion property was improved by using this silane type chain transfer agent.

• Polymer(Korea)
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• v.26 no.6
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• pp.759-766
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• 2002

Regular, spherical and isotropic open-microcellular foams having low density were prepared by the high internal phase emulsion (HIPE) polymerization mainly composed of styrene monomer and water The effects of Polymerization conditions. such as the content of water, divinylbenzene as a crosslinking agent and dodecane as a chain transfer agent, were investigated based on the tell size and foam properties. The microstructural morphology was observed using scanning electron microscopy (SEM) and the compression modulus of the foam was evaluated using compression test. The dropwise feeding of the aqueous phase into the oil phase was more effective than the batch feeding in producing the uniform and stable foam. Agitation speed and surfactant strongly influenced on the cell size and the window size between water droplets. Introduction of chain transfer agent increased the cell size, whereas it decreased the window size. Compression modulus increased with the crosslinking agent, but decreased with the chain transfer agent.

• Journal of the Korean Operations Research and Management Science Society
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• v.35 no.4
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• pp.17-31
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• 2010

This study investigates two-stage return policy and recycling issues in an e-marketplace supply chain consisting of consumers, a retailer and a manufacturer. The manufacturer, a focal company in the e-marketplace supply chain, considers the recycling of commercial returns so offers the retailer a buy-back contract of which transfer payment consists of a wholesale price and a buy-back price. Then, under the given contract offer, the retailer determines a selling price and a return policy to control consumers' demand and return requests. We consider the retailer's opportunistic behavior and supply chain coordination issues based on the principal-agent paradigm. We compare the first-best and second-best optima and conduct comparative static analyses to evaluate the performance results of the buy-back contract and provide important managerial implications.

• Bulletin of the Korean Chemical Society
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• v.16 no.4
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• pp.360-363
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• 1995

The photopolymerization of methyl methacrylate(MMA) with phenylsilane wasperformed. The molecular weights of the poly(MMA) containing SiH moieties were increased with augment of molar ratio of PhSiH3 over MMA by cross-linking via hydrosilation at the expense of isolated yield. Phenylsilane apparently influenced on the photopolymerization as a chain transfer agent and solvent.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.130-140
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• 2018

In the bio-synthesis of poly(3-hydroxybutyrate)(PHB), which is a kind of poly(3-hydroxyalkanoate)(PHA), aimed to control the low molecular weight of PHB and obtain a telechelic PHB. As a result of incubation of R. eutropha at $30^{\circ}C$ with ethylene glycol added as a chain transfer agent, PHB content on the dry cell weight increased up to 24h, however, it decreased after that, and the molecular weight of PHB increased from 9h to 12h, and then, decreased up to 72h. The decrease of the content and the molecular weight of PHB indicates that PHB was decomposed as an energy source in bacterial cells and was incorporated into metabolic pathways. $^1H-NMR$ of the obtained PHB after incubation for 72h was measured to determine the terminal groups of the PHB during incubation. As the results of $^1H-NMR$ measurement, the peaks derived from ethylene glycol in both terminals of PHB were observed. Which indicate that the terminal reaction was caused by the addition of ethylene glycol, and that telechelic PHB having hydroxyl group at the both terminals where molecular weight was controlled was successfully synthesized.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.322-322
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• 2006

Well-defined poly(N-vinylcarbazole), poly(NVC), was synthesized by macromolecular design via interchange of the xanthate (MADIX)/reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of a suitable xanthate-type chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first-order kinetic plot, the molecular weight controlled by the monomer/CTA molar ratio, linear increase in the molecular weight with the conversion, and the ability to extend the chains by the second addition of the monomer. Star polymers having various architectures were also synthesized using this technique.

• Macromolecular Research
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• v.13 no.3
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• pp.236-242
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• 2005

Three dithioester-derived carboxyl acid functionalized RAFT(reversible addition-fragmentation chain transfer) agents, viz. acetic acid dithiobenzoate, butanoic acid dithiobenzoate and 4-toluic acid dithiobenzoate, were used in the RAFT bulk polymerization of styrene, in order to study the effects of the R-group structure on the living nature of the polymerization. By conducting the polymerization with various concentrations of the RAFT agents and at different temperatures, it was found that the R-group structure of the RAFT agents plays an important role in the RAFT polymerization; the bulky structure and radical stabilizing property of the R-group enhances the living nature of the polymerization and allows the polymerization characteristics to be well controlled.

• Macromolecular Research
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• v.17 no.4
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• pp.240-244
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• 2009

High molecular weight(MW), 3-arm star poly(methyl methacrylate)(PMMA) with a narrow MW distribution($M_n$=570,000 g/mol, PDI=1.36) was successfully synthesized by activators regenerated by electron transfer(ARGET) atom transfer radical polymerization(ATRP). The polymerization was carried out with a trifunctional initiator/$CuBr_2$/N,N,N',N",N"-pentamethyldiethy lenetriamine(PMDETA) initiator/catalyst system in the presence of a tin(II) 2-ethylhexanoate [$Sn(EH)_2$] reducing agent at $90^{\circ}C$. The concentration of the copper catalyst was as low as 30 ppm, and a high initiation efficiency of the initiating sites was obtained. The chain-end functionality of the high MW, 3-arm star PMMA was confirmed by a chain extension experiment with styrene via ARGET ATRP, using the same catalyst system.

• Elastomers and Composites
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• v.37 no.1
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• pp.31-38
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• 2002

Polymerization of carboxylated styrene-butadiene latex takes longer time than that of acrylic emulsion due to delocalization of radical in butadiene unit having conjugated double bond. A latex stability is the most important properties owing to use intact without separating polymer from base latex. For reducing polymerization time without decreasing any properties of latex, carbon tetra-chloride which has been used as the most popular chain transfer agent was replaced to combination of tert-dodecylmercaptane and ${\alpha}$-methylstyrene dimer. The replacement yielded reducement or 2 hr in polymerization time. In the increment step, charge amount of acrylic acid was limited to 0.3 part to restrain viscosity enhancement. Just after initial step, addition of 0.1 part acrylamide prevent polymer chain from diffusing between two region followed by giving hardness and final good adhesive force to latex particles.