The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Sadahito Aoshima - One of the best experts on this subject based on the ideXlab platform.
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Metal-Free Living Cationic Polymerization Using Diaryliodonium Salts as Organic Lewis Acid Catalysts
Macromolecules, 2020Co-Authors: Rui Haraguchi, Arihiro Kanazawa, Tsuyoshi Nishikawa, Sadahito AoshimaAbstract:A metal-free initiating system for the living Cationic Polymerization of alkyl vinyl ethers (VEs) and styrene derivatives was developed using diaryliodonium salts as an organic Lewis acid catalyst....
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl_3/alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2015Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses. An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses.
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl 3 /alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2014Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses. An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses.
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Living Cationic Polymerization of vinylnaphthalene derivatives
Journal of Polymer Science Part A, 2013Co-Authors: Yu Shinke, Arihiro Kanazawa, Shokyoku Kanaoka, Sadahito AoshimaAbstract:The living Cationic Polymerization of 6-tert-butoxy-2-vinylnaphthalene (tBOVN), a vinylnaphthalene derivative with an electron-donating group, was achieved with a TiCl4/SnCl4 combined initiating system in the presence of ethyl acetate as an added base at –30 °C. The absence of side reactions at low temperature was confirmed by 1H NMR analysis of the resulting polymer. In contrast to this controlled reaction at –30 °C, reactions performed at higher temperature, such as 0 °C, frequently involved unwanted intramolecular or intermolecular Friedel–Crafts reactions of naphthalene rings due to the high electron density of these rings. The Cationic Polymerization of 6-acetoxy-2-vinylnaphthalene, a derivative with an acetoxy group, was also controlled under similar conditions, but chain transfer reactions were not completely suppressed during the Polymerization of 2-vinylnaphthalene. The glass transition temperature (Tg) of the obtained poly(tBOVN) was 157 °C, a value higher by 94 °C than that of the corresponding styrene derivative. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4828–4834
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Cationic Polymerization of Polar Monomers
Polymer Science: A Comprehensive Reference, 2012Co-Authors: Shokyoku Kanaoka, Sadahito AoshimaAbstract:Cationic Polymerization of polar monomers such as vinyl ethers and styrene derivatives played a critical role in accomplishing ideal living Cationic Polymerization of vinyl-type monomers. Thus, in this chapter, general aspects of Cationic Polymerization are discussed followed by a brief overview of early development of living Cationic Polymerization.
Yusuf Yagci - One of the best experts on this subject based on the ideXlab platform.
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photochemically initiated free radical promoted living Cationic Polymerization of isobutyl vinyl ether
Polymer, 2007Co-Authors: Muhammet U Kahveci, Atilla M Tasdelen, Yusuf YagciAbstract:A new photoinitiating system for living Cationic Polymerization of vinyl ethers such as isobutyl vinyl ether (IBVE) has been reported. The photoinitiating system comprises free radical photoinitiators such as 2,2-dimethoxy-2-phenyl acetophenone (DMPA), benzophenone or thioxanthone, together with an onium salt, such as diphenyliodonium chloride and zinc bromide. In the first step, photochemically generated free radicals are oxidized to the corresponding carbocations which subsequently react with vinyl ether monomer to yield an adduct. In the presence of zinc salt, this adduct initiates living Cationic Polymerization of IBVE.
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Photoinitiated Cationic Polymerization of Unconventional Monomers
Macromolecular Symposia, 2006Co-Authors: Yusuf YagciAbstract:Photoinitiated Cationic Polymerization of unconventional monomers namely, benzoxazines, monothiocarbonates and macromonomers of poly(e-caprolactone) and poly(ethylene oxide) is described. Ring opening Polymerization of benzoxazines and thiocarbonates by direct and sensitized photoinitiation using onium salts was studied. The structures of the resulting polybenzoxazine were complex and related to the ring opening process of the protanated monomer either at through oxygen or nitrogen atoms. In the case of monothiocarbonate, the Polymerization was accompanied with isomerization of thiocarbonate group. The potential use of macromonomers in photoiniated Cationic Polymerization to design complex macromolecular structures such as graft copolymers, water-borne photoresist materials and networks with dangling chains was presented. Photoinduced oxidative Polymerization of thiophene, precursor for conducting polymers, using onium salts was also demonstrated.
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Wavelength flexibility in photoinitiated Cationic Polymerization
Macromolecular Symposia, 2004Co-Authors: Yusuf YagciAbstract:The spectral sensitivity of onium salt photoinitiators in Cationic Polymerization can be tuned from the short wavelength region of the UV spectrum to wavelengths up to the visible region by using direct and indirect activation, respectively. Indirect activation is based on the electron transfer reactions between onium salts and free radical photoinitiators, appropriate sensitizers and compounds capable of forming charge transfer complexes. Bisacylphosphine oxides, dimanganese decacarbonyl in conjunction with alkyl halides and titanocene type photoinitiators such as Irgacure 784 were shown to be useful free radical promoters providing the possibility of performing Cationic Polymerization in the long wavelength and visible region. The synthetic routes to prepare block copolymers by using electron transfer photosensitization and free radical promoted Cationic Polymerization are also described.
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Photoinitiated Cationic Polymerization of monofunctional benzoxazine
Journal of Polymer Science Part A, 2003Co-Authors: Fatmanur Kasapoglu, Yusuf Yagci, Ioan Cianga, Tsutomu TakeichiAbstract:The photoinitiated ring-opening Cationic Polymerization of a monofunctional benzoxazine, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine, with onium salts such as diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate as initiators was examined. The structures of the polymers thus formed were complex and related to the ring-opening process of the protonated monomer either at the oxygen or nitrogen atoms. The phenolic mechanism also contributed, but its influence decreased with decreasing monomer concentration. Thermal properties of the polymers were also investigated by differential scanning calorimetry and thermogravimetric analysis.
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externally stimulated initiator systems for Cationic Polymerization
Progress in Polymer Science, 1998Co-Authors: Yusuf Yagci, Ivo ReetzAbstract:Abstract At present, there is growing interest in Polymerizations initiated by external stimulation, such as photoirradiation, heating or high energy irradiation. Since many industrially important monomers can only be polymerized by a Cationic mechanism, much effort has been made to develop systems that produce initiating cations upon external stimulation. In this article, the latest developments in externally stimulated systems for Cationic Polymerization are reviewed. The goal is, furthermore, to show differences as well as parallels between systems for different modes of external stimulation.
Shokyoku Kanaoka - One of the best experts on this subject based on the ideXlab platform.
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl_3/alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2015Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses. An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses.
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl 3 /alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2014Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses. An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses.
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Living Cationic Polymerization of vinylnaphthalene derivatives
Journal of Polymer Science Part A, 2013Co-Authors: Yu Shinke, Arihiro Kanazawa, Shokyoku Kanaoka, Sadahito AoshimaAbstract:The living Cationic Polymerization of 6-tert-butoxy-2-vinylnaphthalene (tBOVN), a vinylnaphthalene derivative with an electron-donating group, was achieved with a TiCl4/SnCl4 combined initiating system in the presence of ethyl acetate as an added base at –30 °C. The absence of side reactions at low temperature was confirmed by 1H NMR analysis of the resulting polymer. In contrast to this controlled reaction at –30 °C, reactions performed at higher temperature, such as 0 °C, frequently involved unwanted intramolecular or intermolecular Friedel–Crafts reactions of naphthalene rings due to the high electron density of these rings. The Cationic Polymerization of 6-acetoxy-2-vinylnaphthalene, a derivative with an acetoxy group, was also controlled under similar conditions, but chain transfer reactions were not completely suppressed during the Polymerization of 2-vinylnaphthalene. The glass transition temperature (Tg) of the obtained poly(tBOVN) was 157 °C, a value higher by 94 °C than that of the corresponding styrene derivative. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4828–4834
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Cationic Polymerization of Polar Monomers
Polymer Science: A Comprehensive Reference, 2012Co-Authors: Shokyoku Kanaoka, Sadahito AoshimaAbstract:Cationic Polymerization of polar monomers such as vinyl ethers and styrene derivatives played a critical role in accomplishing ideal living Cationic Polymerization of vinyl-type monomers. Thus, in this chapter, general aspects of Cationic Polymerization are discussed followed by a brief overview of early development of living Cationic Polymerization.
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Overview of Living Cationic Polymerization. Part 3: Living Cationic Polymerization of Isobutene and Styrenes
NIPPON GOMU KYOKAISHI, 2011Co-Authors: Shokyoku Kanaoka, Sadahito AoshimaAbstract:The final installment of the three-part series of a special lecture for living Cationic Polymerization focuses on recent progress in living Polymerization of isobutene and styrene derivatives. Unique and new initiating systems for living Polymerization have been developed for isobutene and styrenes. This final article focuses on active living catalysts for both monomers, and water-tolerant systems for styrenes.
Arihiro Kanazawa - One of the best experts on this subject based on the ideXlab platform.
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Metal-Free Living Cationic Polymerization Using Diaryliodonium Salts as Organic Lewis Acid Catalysts
Macromolecules, 2020Co-Authors: Rui Haraguchi, Arihiro Kanazawa, Tsuyoshi Nishikawa, Sadahito AoshimaAbstract:A metal-free initiating system for the living Cationic Polymerization of alkyl vinyl ethers (VEs) and styrene derivatives was developed using diaryliodonium salts as an organic Lewis acid catalyst....
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl_3/alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2015Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses. An initiating system composed of GaCl_3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl_3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl_3 and the alkylbenzene, as confirmed by UV–vis and ^71Ga NMR analyses.
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New initiating systems for Cationic Polymerization of plant-derived monomers: GaCl 3 /alkylbenzene-induced controlled Cationic Polymerization of β-pinene
Polymer Journal, 2014Co-Authors: Yukari Karasawa, Arihiro Kanazawa, Shokyoku Kanaoka, Madoka Kimura, Sadahito AoshimaAbstract:An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. Alkylbenzenes such as pentamethylbenzene and hexamethylbenzene were shown to function as suitable additives for the Polymerization of β-pinene, an alkene monomer with low reactivity, although the alkylbenzenes are much less basic than conventional additives such as esters and ethers for base-assisting living Cationic Polymerization. For example, when two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction, i.e., control of an active–dormant equilibrium, was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses. An initiating system composed of GaCl3 and an alkylbenzene was demonstrated to be highly effective for the controlled Cationic Polymerization of a plant-derived monomer, β-pinene. When two equivalents of hexamethylbenzene were added to GaCl3 in conjunction with 2-chloro-2,4,4-trimethylpentane as an initiator, Cationic Polymerization of β-pinene successfully proceeded in a living manner at –78 °C. Successful control over the reaction was attributed to the formation of a complex between GaCl3 and the alkylbenzene, as confirmed by UV–vis and 71Ga NMR analyses.
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Living Cationic Polymerization of vinylnaphthalene derivatives
Journal of Polymer Science Part A, 2013Co-Authors: Yu Shinke, Arihiro Kanazawa, Shokyoku Kanaoka, Sadahito AoshimaAbstract:The living Cationic Polymerization of 6-tert-butoxy-2-vinylnaphthalene (tBOVN), a vinylnaphthalene derivative with an electron-donating group, was achieved with a TiCl4/SnCl4 combined initiating system in the presence of ethyl acetate as an added base at –30 °C. The absence of side reactions at low temperature was confirmed by 1H NMR analysis of the resulting polymer. In contrast to this controlled reaction at –30 °C, reactions performed at higher temperature, such as 0 °C, frequently involved unwanted intramolecular or intermolecular Friedel–Crafts reactions of naphthalene rings due to the high electron density of these rings. The Cationic Polymerization of 6-acetoxy-2-vinylnaphthalene, a derivative with an acetoxy group, was also controlled under similar conditions, but chain transfer reactions were not completely suppressed during the Polymerization of 2-vinylnaphthalene. The glass transition temperature (Tg) of the obtained poly(tBOVN) was 157 °C, a value higher by 94 °C than that of the corresponding styrene derivative. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4828–4834
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recent progress in living Cationic Polymerization of vinyl ethers
Chemistry Letters, 2010Co-Authors: Arihiro Kanazawa, Shokyoku Kanaoka, Sadahito AoshimaAbstract:Recent advancements in living Cationic Polymerization of vinyl ethers are reviewed, especially focusing on newly developed initiating systems using various Lewis acid catalysts. In concert with the...
Yasushi Maeda - One of the best experts on this subject based on the ideXlab platform.
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hcl et2o catalyzed metal free raft Cationic Polymerization one pot transformation from metal free living Cationic Polymerization to raft radical Polymerization1
Macromolecules, 2015Co-Authors: Shinji Sugihara, Naoto Konegawa, Yasushi MaedaAbstract:The metal-free RAFT Cationic Polymerization (MRCP) of vinyl ethers (VEs) mediated by HCl·Et2O and 1-isobutoxyethyl ethanedithioate (IDTA) as a RAFT cationogen was demonstrated. The IDTA was efficiently catalyzed and the Cationic Polymerization was initiated by the HCl·Et2O, allowing good control over the molecular weight, polydispersity, and chain end structure of the resulting polyVEs. The propagation step is considered to involve a reversible addition–fragmentation chain transfer (RAFT) to the growing carboCationic species. Thus, the resulting polyVEs can exhibit high number-average end functionality at the RAFT terminal group, depending on the [IDTA]0/[HCl]0 ratio. The polymers obtained by this process could be used as macro-chain transfer agents for the RAFT radical Polymerization of radically polymerizable monomers such as (meth)acrylates and styrenes to synthesize novel block copolymers. Significantly, this MRCP system allows a one-pot transformation from MRCP to RAFT radical Polymerization as a res...
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transformation of living Cationic Polymerization of vinyl ethers to raft Polymerization mediated by a carboxylic raft agent
Macromolecules, 2012Co-Authors: Shinji Sugihara, Kenta Yamashita, Keiji Matsuzuka, Isao Ikeda, Yasushi MaedaAbstract:Novel block copolymers were synthesized by the transformation of living Cationic Polymerization of vinyl ethers into reversible addition–fragmentation chain transfer (RAFT) Polymerization using two types of RAFT agents. Examples include Cationically polymerizable monomer of either isobutyl vinyl ether or 2-methoxyethyl vinyl ether (MOVE) and radically polymerizable monomer such as ethyl acrylate, styrene, tert-butoxy styrene, and N-isopropylacrylamide (NIPAM). The key to success in the block coPolymerization is to utilize a RAFT agent of the carboxylic trithiocarbonate/SnBr4 initiation system in the presence of an additive such as ethyl acetate and dioxane for living Cationic Polymerization. The living Cationic Polymerization was initiated from a proton derived from the carboxylic RAFT agent. After a certain period, the Polymerization was quenched and the RAFT group as a counteranion was concurrently recovered, followed by the RAFT process of radical Polymerization using azobis(isobutyronitrile) at 70 °C....