• Macromolecular Research
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• v.17 no.8
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• pp.557-562
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• 2009

The free radical polymerization of styrene was initiated with azobis(isobutyronitrile) in the presence of benzene sulfonyl chloride. Analysis of the terminal structures of the obtained polystyrene with $^1H$ NMR spectroscopy revealed the presence of a phenyl sulfonyl group at the ${\alpha}$-end and a chlorine atom at the ${\omega}$-end of each polystyrene chain. The terminal chlorine atom in the polystyrene chains was further confirmed through atom transfer radical polymerization (ATRP) of styrene and methyl acrylate using the obtained polystyrenes as macroinitiators and CuCl/2,2'-bipyridine as the catalyst system. GPC traces of the products obtained in ATRP at different reaction times were clearly shifted to higher molecular weight direction, indicating that nearly all the macroinitiator chains initiated ATRP of the second monomers. In addition, the number-average molecular weights of the polystyrenes increased directly proportional to the monomer conversions, and agreed well with the theoretical ones.

• Bulletin of the Korean Chemical Society
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• v.20 no.11
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• pp.1355-1358
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• 1999

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.398-403
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• 1980

Carboxyl-terminated polybutadiene was prepared by free-radical polymerization using 4,4'-azobis-[4-cyano valeric acid] as an initiator and the effect of initiator concentration on polymer properties was investigated. Polymerization of the carboxyl-terminated polybutadiene was carried out varying the initiator concentration reacting with a constant butadiene concentration. The carboxyl weight percent decreased with increasing initiator concentration. The conversion was proportional to the square root of initiator concentration, giving a functionality greater than 2.0 which is consistent with the general tendency of free radical polymerization.

• Bulletin of the Korean Chemical Society
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• v.24 no.2
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• pp.167-172
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• 2003

Alkyliron(Ⅲ) porphyrins, n-butyliron(Ⅲ) tetraphenylporphyrin, (TPP)Fe-Bu and n-butyliron(Ⅲ) tetrakis-(pentafluorophenyl)porphyrin, $(F_{20}TPP)Fe-Bu$ have been evaluated as suitable for olefin free-radical polymerization. Butyl radicals dissociated from n-butyliron(Ⅲ) porphyrin initiated the polymerization reaction, but the ratio of the propagation was low. The GCMS analysis of the reaction mixture of nbutyliron(Ⅲ) porphyrin and styrene has revealed several products containing two butyl groups, while traces of b-hydrogen-abstracted products were observed. The crystal structure of (TPP)Fe-Bu has been determined. The structure of the n-butyliron(Ⅲ) porphyrin reveals the compound containing five-coordinated iron with the average Fe-N distance of 1.973(1) Å and Fe-C of 2.030(2) Å. The iron atom is displaced by 0.137Å from a four nitrogen mean plane. Crystal system is triclinic, and space group is P-1.

• Elastomers and Composites
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• v.50 no.2
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• pp.119-125
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• 2015

Because of their low surface free energy and absence of polar groups at the surface, polyolefins are substrates whose wetting and adhesion are very difficult. Free radical grafting of monomers to backbone polymer is one of the most attractive ways for the chemical modification of polymers. Synthesis of graft copolymer through graft polymerizations of PE and/or PP with phthalic anhydride (PhAn) was made and FTIR spectra of the graft polymer were the examined. And also the effects of phthalic anhydride content on the grafting ratio, thermal properties and contact angle of the graft polymer were examined.

• Bulletin of the Korean Chemical Society
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• v.17 no.3
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• pp.257-262
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• 1996

p-(2-Vinyloxyethoxy)benzylidenemalononitrile 2 and methyl p-(2-vinyloxyethoxy)benzylidenecyanoacetate 3 was prepared by the condensation of p-(2-vinyloxyethoxy)benzaldehyde 1 with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2 and 3 polymerized quantitatively with radical initiators in γ-butyrolactone solution at 65 ℃. The trisubstituted terminal double bond participated in the vinyl polymerization and radical polymerization of 2 and 3 led to swelling polymers 4 and 5 that were not soluble in common solvents due to cross-linking. Under the same polymerization conditions ethylvinyl ether polymerized well with model compounds of p-methoxybenzylidenemalononitrile 6 and methyl p-methoxybenzylidenecyanoacetate 7, respectively, to give 1:1 alternating copolymers 8 and 9 in high yields. Polymers 4 and 5 showed a thermal stability up to 300 ℃ without any characteristic Tg peaks in DSC thermograms. Alternating copolymers 8 and 9 were soluble in common solvents such as acetone and DMSO, and the inherent viscosities of the polymers were in the range of 0.36-0.74 dL/g. Films cast from acetone solution were cloudy and tough and Tg values obtained from DSC thermograms were in the range of 59-60 ℃.

• Nuclear Engineering and Technology
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• v.8 no.3
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• pp.159-168
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• 1976

Acrylic acid has been grafted onto nylon fabric with ceric salts and ${\gamma}$-rays from Co-60 as initiators. The distribution of molecular weight of the grafted polyacrylic acid has been determined and it was found that the ratio of weight-average and number-average molecular weight was higher in room temp. than in low temp. (-184$^{\circ}C$). The weight-average molecular weight of the polyacrylic acid was calculated from viscosity measurements in sodium hydroxide solution. The factors affecting graft polymerization of acrylic acid onto nylon were examined. A possible mechanism that the oxidation of nylon probably takes place at the methylene group attached to nitrogen to give a free-radical was discussed.

• Polymer Science and Technology
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• v.8 no.1
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• pp.4-11
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• 1997

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.348-350
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• 2000

• Macromolecular Research
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• v.17 no.1
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• pp.14-18
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• 2009

The acceleration effect of various organic acids, such as methanesulfonic acid (MSA), ethanesulfonic acid (ESA), 4,4'-sulfonyldibenzoic acid (SDA), diphenylacetic acid (DPAA), and $\rho$-toluenesulfonic acid (TSA), on the rate of styrene bulk polymerization with 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) and benzoyl peroxide (BPO) was investigated. The addition of organic acids significantly accelerated the rate. Among these organic acids, DPAA showed an efficient rate-accelerating effect with living nature of polymerization. When DPAA was used as a rate-accelerating additive for TEMPO-mediated living free radical polymerization (LFRP), the rate of polymerization was dramatically enhanced, the linearity of reaction kinetics was successfully maintained, and the polydispersity was effectively controlled.