• Title, Summary, Keyword: polymerization

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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.

Degree of Polymerization of Graft Copolymers of Methyl Methacrylate on Silk in the Presence of Cupric Salt (동염존재하의 견사에 대한 graft 공중합에 있어서의 중합도)

  • 신현우
    • Textile Science and Engineering
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    • v.10 no.3
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    • pp.1-6
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    • 1973
  • The degree of polymerization of the PMMA contained in the silk fibre, which was obtained by graft copolymerization by using Cu(II)/H$_2$O$_2$as an initiator was studied under the various conditions of polymerization. For both the grafted PMMA and free PMMA formed out side the silk fibre, the degrees of polymerization were found as follows. (1) The degree of polymerization was roughly proportional to the concentration of monomer. (2) With increasing concentration of cupric salt, the degree of polymerization was decreased gradually. (3) The effect of hydrogen peroxide on the degree of polymerization was considerable, and D.P. has a maximum value at concentration of 10-$^1$mole/l and the curve of degree of polymerization was similar to that of graft-on. (4) The maximum value of graft-on and that of the degree of polymerization were at 30 min. 70$^{\circ}C$. The value of graft-on after 30 min. was steady, however, the degree of obtained polymerization was decreased. (5) The degree of polymerization was affected considerably by the temperature of the polymerization and its maximum value was attained at 70$^{\circ}C$ as in graft-on. (6) The degree of polymerization of the graft PMMA is generally larger than that of the free PMMA outside of the fibre.

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Core-Shell Poly(Styrene/Sulfonated N-hydroxy Ethyl Aniline) Latex Particles Prepared by Chemical Oxidative Polymerization in Emulsion Polymerization

  • Shin Jin-Sup;Lee Jung-Min;Suzuki Kiyoshi;Nomura Mamoru;Cheong In-Woo;Kim Jung-Hyun
    • 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.

Photo-Induced Cationic Ring-Opening Polymerization of 4-Methylene-2-styryl-1,3-dioxolane by Benzylsulfonium Salt

  • Park, Jaekyeung
    • Macromolecular research
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    • v.9 no.4
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    • pp.206-209
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    • 2001
  • One of the approaches to obtain functional polymer is polymerization of a monomer having two functional groups. Although polymerization of a monomer having two different types of functional group is general, the author has been interested in the polymerization of a monomer having two similar types of functional group. This work shows the preparation and selective polymerization of 4-methylene-2-styryl-1,3-dioxolane having two similar reactive double bonds via cationic polymerization at ambient temperature. Cationic ring-opening polymerization of 4-methylene-2-styryl-1,3-dioxolane using benzylsulfonium salt as a photo-initiator quantitatively afforded high molecular weight of poly(keto-ether).

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Comparative Study of Physical Properties of Functional Ophthalmic Hydrogel Lens Using Photo and Thermal Polymerization

  • Kim, Duck-Hyun;Seok, Jae-Wuk;Sung, A-Young
    • Journal of the Chosun Natural Science
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    • v.10 no.3
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    • pp.148-153
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    • 2017
  • In this study, HEMA, MMA, AA, and EGDMA were used as basic combinations for manufacturing hydrophilic lenses for ophthalmic applications. In addition, AIBN (thermal polymerization initiator), 2H2M (photo polymerization initiator), and 3-hydroxypyridine (additive) were used to manufacture hydrophilic ophthalmic lenses through thermal polymerization and photo polymerization before their physical properties were measured. The results showed that when ophthalmic lenses were prepared via thermal polymerization and photo polymerization using 3-hydroxypyridine as an additive, their optical and physical properties and surface structures were different in each case, but they all satisfied the physical properties required for ophthalmic lenses.

Titanium Complexes: A Possible Catalyst for Controlled Radical Polymerization

  • Kwark, Young-Je;Kim, Jeong-Han;Novak Bruce M.
    • Macromolecular research
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    • v.15 no.1
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    • pp.31-38
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    • 2007
  • Pentamethylcyclopentadienyltitanium trichloride, bis(cyclopentadienyl)titanium dichloride ($Cp_2TiCl_2$), and bis(pentamethylcyclopentadienyl)titanium dichloride were used in the polymerization of styrene without the aid of Group I-III cocatalysts. The properties of the resulting polymer indicated that polymerization was more controlled than in thermal polymerization. The kinetic studies indicated that a lower level of termination is present and that the polymer chain can be extended by adding an additional monomer. To elucidate the mechanism of polymerization, a series of experiments was performed. All results supported the involvement of a radical mechanism in the polymerization using $Cp_2TiCl_2$. The possibility of atom transfer radical polymerization (ATRP) mechanism was investigated by isolating the intermediate species. We could confirm the activation step from the reaction of 1-PEC1 with $Cp_2TiCl$ by detecting the coupling product of the generated active radicals. However, the reversible deactivation reaction competes with other side reactions, and it detection was difficult with our model system.

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.

Graft Polymerization of Methyl Methacrylate onto Cotton Fiber -Comparison of two step graft polymerization and emulsion graft polymerization- (면섬유에 Methyl Methacrylate의 그라프트중합 - 이단계 그라프트중합과 유화 그라프트중합의 비교 -)

  • Bae Hyun-Sook;Kim Sung-Reon
    • Journal of the Korean Society of Clothing and Textiles
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    • v.13 no.1
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    • pp.89-97
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    • 1989
  • Graft polymerization of MMA onto cotton fiber was carried out in two ways, two step graft polymerization and one step emulsion graft polymerization, using tetravalent cerium ion as an initiator. At two step graft polymerization, the first step was the pretreatment of cotton fiber with an aqueous initiator solution and the second was the grafting pretreated cotton fiber in the monomer solution. In case of one step emulsion graft polymerization, MMA was emulsified with SLS in initiator solution. Under the various graft polymerization conditions, graft yield, graft efficiency and from the Arrhenius plot the apparent activation energy were compared. The results of this study were as follows: 1. Graft yield and graft efficiency of emulsion graft polymerization were higher than those of two step graft polymerization. 2. In case of two step graft polymerization, graft yield was affected by the pretreatment time of cotton fiber with an aqueous initiator solution. And graft yield of emulsion graft polymerization was increased with the concentration of emulsifier below cmc of SLS and was decreased thereafter. 3. Elevation of temperature resulted increase in graft yield for both grafting methods. The apparent activation energy of emulsion graft pelymerzation was lower than that of two step graft polymerization. 4. Increased reaction time increased in graft yield, but decreased in graft efficiency. 5. Moisture regain of grafted cotton was decreased with graft yield.

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Dispersion Polymerization of Acrylamide in t-Butyl Alcohol/Water Media

  • Lee, Ki-Chang;Lee, Seung-Eun;Park, Yoo-Jin;Song, Bong-Keun
    • Macromolecular research
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    • v.12 no.2
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    • pp.213-218
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    • 2004
  • We have performed dispersion polymerization of acrylamide in tert-butyl alcohol/water mixture-using hydroxypropyl cellulose and ammonium persulfate as the stabilizer and the initiator, respectively - to study the effects that the concentration of monomer, initiator, and stabilizer, the tert-butyl alcohol/water ratios as polymerization media, and the reaction temperature have on, among other things, the polymerization kinetics, particle sizes, and molecular weights. The polymerization rate increased upon increasing the concentration of the monomer, initiator, and stabilizer, the water content in the tert-butyl alcohol/water media, and the polymerization temperature. The average particle size of the lattices increased upon increasing the concentration of initiator, the polymerization temperature, and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing the concentration of monomer and stabilizer. The viscosity-average molecular weight increased upon increasing the concentration of monomer and stabilizer and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing both the concentration of initiator and the polymerization temperature.

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.