• Title, Summary, Keyword: living radical polymerization

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Reversible Addition-Fragmentation Chain Transfer (RAFT) Bulk Polymerization of Styrene: Effect of R-Group Structures of Carboxyl Acid Group Functionalized RAFT Agents

  • Lee Jung Min;Kim Ok Hyung;Shim Sang Eun;Lee Byung H.;Choe Soonja
    • 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.

The Effect of Camphorsulfonic Acid in TEMPO-Mediated Bulk and Dispersion Polymerization of Styrene

  • Oh Sejin;Kim Gijung;Ko Narae;Shim Sang Eun;Choe Soonja
    • Macromolecular Research
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    • v.13 no.3
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    • pp.187-193
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    • 2005
  • The TEMPO-mediated living free-radical bulk and dispersion polymerization of styrene in the presence of camphorsulfonic acid (CSA) are investigated. In the absence of TEMPO and CSA in the bulk polymerization, a conversion of $93\%$ is achieved within 6 hr of polymerization. When only TEMPO is involved in this polymerization, the pseudo-living free-radical polymerization is well achieved, however, the polymerization rate becomes quite slow. This retardation of the polymerization rate is solved by the addition of a low concentration of CSA. In the TEMPO-mediated dispersion polymerization in the presence of CSA, similar trends in the conversion, kinetics, and PDI are observed as those observed in the case of bulk polymerization. When only TEMPO is used in the dispersion polymerization, the resulting particle size becomes quite broad, due to the prolonged polymerization time. However, when a 1.0 molar ratio of CSA to TEMPO is added to the TEMPO-mediated dispersion polymerization, fairly mono-disperse PS microspheres having an average size of 5.83 $\mu$m and a CV of 3.4$\%$ are successfully obtained, due to the narrow molecular weight distribution of the intermediate oligomers and shortening of the polymerization time. This result indicates that the addition of CSA to the TEMPO-mediated bulk and the use of dispersion polymerization not only shortens the polymerization time, but also greatly improves the uniformity of the microspheres.

Preparation of Polyolefin Based Segmented Copolymers Through Controlled Radical Polymerization Technique (조절 라디칼 중합법에 의한 폴리올레핀 기반 분절 공중합체의 제조)

  • Hong, Sung-Chul;Lee, Seong-Hoon;Cho, Hyun-Chul
    • Elastomers and Composites
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    • v.44 no.3
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    • pp.209-221
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    • 2009
  • Polyolefins are important commodity polymers with the largest volume of business owing to their outstanding combination of cost performance and excellent physical properties. However, the lack of functional groups often has limited their end uses, such as compatibilizer, modifier and adhesive, where the interaction with other materials is especially important. The incorporation of functional groups as polymer segments to afford block or graft polyolefin copolymers has been extensively investigated in the context of the functional polyolefin hybrids. Living polymerization processes have been considered to be an efficient method to prepare the polyolefin hybrids with precisely controlled architecture and compositions. Among the living polymerization techniques, controlled/"living" radical polymerization (CRP) methods are very effective not only because of the controllability of polymerization but also because of the versatility of monomers and polymerization conditions. In this review paper, progresses on the preparations of polyolefin graft or block copolymers through CRP techniques are summarized. The commodity polymers such as polyisobutylene, polyethylene and polypropylene are combined with polar segments such as polyacrylate, polymethacrylate, polystyrene to yield functionalized polyolefins.

Polymerization of Vinyl Monomers Initiated by Thianthrene Cation Radical with Potential Biological Activity

  • Lee, Beomgi;Kim, Seongsim;Park, Jaeyoung;Cheong, Hyeonsook;Noh, Ji Eun;Woo, Hee-Gweon
    • Journal of the Chosun Natural Science
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    • v.5 no.2
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    • pp.127-130
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    • 2012
  • Polymerization of vinyl monomers is promoted by thianthrene cation radical as a part of our research concerning the reactions of various agents with readily isolable, yet highly reactive species and elucidate the biological activity. Thianthrene cation radical initiated the homopolymerization and copolymerization of styrene and ethyl vinyl ether. The polymerization yields decreased as the concentration of phenylacetylene or diphenylethylene increased. Such polymereization by cationic thianthrene radical could provide some clues for the reaction in living animals. Comments on possible polymerization mechanisms were suggested.

Study on the Polymerization Characteristics of Isoprene through Nitroxide Mediated Controlled/"living" Radical Polymerization Techniques (Nitroxide 매개 리빙라디칼 중합법에 의한 isoprene의 중합특성에 관한 연구)

  • Hong, Sung-Chul
    • Elastomers and Composites
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    • v.44 no.1
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    • pp.55-62
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    • 2009
  • In this study, investigation on the polymerization characteristics of isoprene through nitroxide mediated controlled/"living" radical polymerization techniques was attempted. In the presence of acetol, linear increase of isoprene conversion with time and low polydispersities of the resulting polymers ($M_w/M_n$ < 1.5) were observed, which suggest successful controlled/"living" radical polymerization of isoprene. The microstructure of the resulting polyisoprene was composed of $\sim$ 22% of 3, 4, $\sim$30% of 1, 4-cis and $\sim$ 48% of 1, 4-trans. The optimum polymerization temperature was 145 $^{circ}C$, below which no significant polymerization behavior was observed. Non-cyclic nitroxide, such as di-tert-butyl nitroxide (DTBN) could not mediate the polymerization, whereas cyclic nitroxides (2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (TEMPO) and 4-oxo-2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (oxoTEMPO)) were successfully employed for the polymerization. However, isoprene dimerization reaction through Diels-Alder process was also observed at the given polymerization condition, which afforded a significant amount of limonene. Isoprene thermal autoinitiation was also possible, which was, however, considered to be not significant under the given polymerization condition.

Transition Metal-Mediated Living Radical Polymerization toward Precision Functional Polymers via Catalyst Design

  • Sawamoto, Mitsuo;Ouchi, Makoto
    • Proceedings of the Polymer Society of Korea Conference
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    • pp.93-94
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    • 2006
  • This lecture will present an overview of recent advances in our transition metal-mediated living radical polymerization, particularly focused on catalyst design and precision synthesis of functional polymers. Selected topics will include: (A) Design of Transition Metal Complexes: Evolution of Catalysts (B) New Ruthenium and Iron Catalysts: Active and Versatile (C) Functional Methacrylates for Advanced Functional Polymers (D) Functional Star Polymers: Microgel Cores for Metal Catalysts.

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Cu Catalyst System with Phosphorous Containing Bidendate Ligand for Living Radical Polymerization of MMA

  • Hong Sung Chul;Shin Ki Eun;Noh Seok Kyun;Lyoo Won Seok
    • Macromolecular Research
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    • v.13 no.5
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    • pp.391-396
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    • 2005
  • The polymerization of methyl methacrylate (MMA) was carried out using CuBr/bidentate phosphorus ligand catalyst systems. MMA polymerization with CuBr/phosphine-phosphinidene (PP) exhibited high conversion ($\~80\%$) in 5 h at $90^{\circ}C$ along with a linear increase of ln($[M]_0/[M]$) versus time, indicating constant concentration of the propagating radicals during the polymerization. The molecular weight of the prepared PMMA tended to increase with conversion, suggesting the living polymerization characteristic of the system. On the other hand, a large difference between the measured and theoretical molecular weight and a broad molecular weight distribution were observed, implicating possible incomplete control over the polymerization. This may have been caused by the low deactivation rate constant ($\kappa_{deact}$) of the system. The low $\kappa_{deact}$, would result in irreversible generation of radicals instead of reversible activation/deactivation process of ATRP. Polymerizations performed at different ligand to CuBr ratios and different monomer to initiator ratios did not afford better control over the polymerization, suggesting that the controllability of CuBr/phosphorus ligand system for ATRP is inherently limited.

Rate-acceleration of TEMPO-mediated Polymerization of Styrene in the Presence of Various Acids

  • Hong, Chang-Kook;Jang, Heang-Sin;Hong, Sang-Hyun;Shim, Sang-Eun
    • 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.

Iron Catalyzed Atom Transfer Radical Polymerization of Methyl Methacrylate Using Diphenyl-2-pyridylphosphine as a Ligand

  • Xue, Zhigang;Noh, Seok-Kyun;Lyoo, Won-Seok
    • Macromolecular Research
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    • v.15 no.4
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    • pp.302-307
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    • 2007
  • The living radical polymerization of methyl methacrylate (MMA) by atom transfer radical polymerization, (ATRP) employing a $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine (PyP) catalytic system (X=Cl, Br), was investigated using several initiators and solvents at various temperatures. Most of the polymerizations with the PyP ligand were well controlled, with a linear increase in the number average molecular weights ($M_n$) vs. conversion, with relatively low molecular weight distributions ($M_w/M_n=1.2-1.4$) throughout the reactions. The measured weights matched those of the predicted values. The ethyl-2-bromoisobutyrate (EBriB) initiated ATRP of MMA, with the $Fe(II)X_2/diphenyl-2-pyridyl$ phosphine catalytic system (X=Cl, Br), was better controlled in p-xylene at $80^{\circ}C$ than the other solvents used in this study.

Synthesis of block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) by ATRP (atom transfer radical polymerization) (ATRP(atom transfer radical polymerization)에 의한 polystyrene과 poly ethylene glycol methyl ether methacrylate(PEGMA)의 블록 공중합체의 합성)

  • Kim, Sang-Hern
    • Journal of the Korean Applied Science and Technology
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    • v.26 no.3
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    • pp.306-316
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    • 2009
  • In this study, block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) by ATRP(atom transfer radical polymerization) method was synthesized. 4 arm-molecule which contained halogen atom was synthesized for an initiator. With 4 arm-molecule monodispered polystyrene were synthesized by ATRP method. The molecular change of synthesized monodispersed polystyrene with respect to time was investigated and living polymer characteristic was confirmed. Block copolymer of polystyrene and polyethylene glycol methyl ether methacrylate(PEGMA) was synthesized by ATRP with macroinitiator which was synthesized from the monodispersed polystyrene(Mn=12000). The molecular weight of obtained PS-b-PEGMA was 22,000.