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Tsutomu Yokozawa - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Mizoroki‐Heck coupling Polymerization as a catalyst‐transfer condensation Polymerization for synthesis of poly(p‐phenylenevinylene)
Journal of Polymer Science Part A: Polymer Chemistry, 2014Co-Authors: Masataka Nojima, Ryosuke Saito, Yoshihiro Ohta, Tsutomu YokozawaAbstract:Mizoroki-Heck coupling Polymerization of 1,4-bis[(2-ethylhexyl)oxy]-2-iodo-5-vinylbenzene (1) and its bromo counterpart 2 with a Pd initiator for the synthesis of poly(phenylenevinylene) (PPV) was investigated to see whether the Polymerization proceeds in a Chain-Growth Polymerization manner. The Polymerization of 1 with tBu3PPd(Tolyl)Br (10) proceeded even at room temperature when 5.5 equiv of Cy2NMe (Cy = cyclohexyl) was used as a base, but the molecular weight distribution of PPV was broad. The Polymerization of 2 hardly proceeded at room temperature under the same conditions. In the Polymerization of 1, PPV with H at one end and I at the other was formed until the middle stage, and the polymer end groups were converted into tolyl and H in the final stage. The number-average molecular weight (Mn) did not increase until about 90% monomer conversion and then sharply increased after that, indicating conventional step-Growth Polymerization. The occurrence of step-Growth Polymerization, not catalyst-transfer Chain-Growth Polymerization, may be interpreted in terms of low coordination ability of H-Pd(II)-X(tBu3P) (X = Br or I), formed in the catalytic cycle of the Mizoroki-Heck coupling reaction, to π-electrons of the PPV backbone; reductive elimination of H-X from this Pd species with base would take place after diffusion into the reaction mixture. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 543–551
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Precision Synthesis of n-Type π-Conjugated Polymers in Catalyst-Transfer Condensation Polymerization
ACS Macro Letters, 2012Co-Authors: Tsutomu Yokozawa, Yutaka Nanashima, Yoshihiro OhtaAbstract:Recent developments in catalyst-transfer condensation Polymerization, which proceeds in a Chain-Growth Polymerization manner, have made it possible to synthesize well-defined π-conjugated polymers with controlled molecular weight and low polydispersity, as well as block copolymers and gradient copolymers. However, catalyst-transfer condensation Polymerization has been limited to the Polymerization of donor monomers (such as thiophene) for the synthesis of p-type π-conjugated polymers. Here, we highlight several recent advances in catalyst-transfer condensation Polymerization leading to n-type π-conjugated polymers. The Kumada–Tamao coupling Polymerization of Grignard pyridine monomers yields well-defined poly(pyridine-3,5-diyl) and poly(pyridine-2,5-diyl) with a broad molecular weight distribution. Monomers consisting of strong acceptor and weak donor moieties also undergo catalyst-transfer Polymerization; well-defined poly(fluorene benzothiaziazole) was obtained by Suzuki–Miyaura coupling Polymerization ...
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Chain-Growth Condensation Polymerization
Polymer Science: A Comprehensive Reference, 2012Co-Authors: Tsutomu YokozawaAbstract:Condensation polymers, including π-conjugated polymers, with well-defined molecular weight and low polydispersity can be synthesized by changing the Polymerization mechanism from a step-Growth to a Chain-Growth Polymerization. The change of mechanism has been attained by (1) activation of the polymer end group by changing the substituent effects between the monomer and the polymer; (2) phase-transfer Polymerization in a biphasic system comprising a monomer storage phase and a Polymerization phase; (3) transfer of the reactive species, derived from the initiator, to the polymer end group; and (4) activation of the polymer end group by transfer of the catalyst to it.
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Reaction Control in Condensation Polymerization
Advances in Polymer Science, 2008Co-Authors: Tsutomu Yokozawa, Naomi Ajioka, Akihiro YokoyamaAbstract:Recent progress in the reaction control of condensation Polymerization is described. In the past, the reactions in condensation Polymerization had been improved for the purpose of production of high molecular weight polymer with more convenient methods. In recent years, chemoselective, regioselective, and stereoselective condensation Polymerizations have been developed. Furthermore, it has been revealed that most condensation Polymerizations possess the fundamental tendency to yield cyclic polymers as stable end products when the reactions are optimized for quantitative reaction. When the reactivity of a functional group of a monomer was enhanced after the other functional group of the monomer was reacted, condensation Polymerization of AA and BB monomers afforded polymer with high molecular weight, even under nonstoichiometric conditions, and condensation Polymerization of AB monomer involved a Chain-Growth Polymerization mechanism to yield polymer with narrow molecular weight distribution.
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Chain Growth Polymerization for the synthesis of polyfluorene via suzuki miyaura coupling reaction from an externally added initiator unit
Journal of the American Chemical Society, 2007Co-Authors: Akihiro Yokoyama, Hirofumi Suzuki, Yasuhiro Kubota, Kazuei Ohuchi, Hideyuki Higashimura, Tsutomu YokozawaAbstract:Palladium-catalyzed polycondensation of 2-(7-bromo-9,9-dioctyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1a) with tBu3PPd(Ph)Br (2) via Suzuki−Miyaura coupling reaction was investigated. The Polymerization in a mixture of THF and 2 mol/L aqueous solution of Na2CO3 proceeded smoothly at room temperature and afforded well-defined polyfluorenes with narrow molecular weight distributions. MALDI-TOF mass spectroscopy showed that the obtained polymers have a phenyl group at one end. The relationships of conversion to number-average molecular weight (Mn) and feed ratio to Mn were linear. These results demonstrate that this organometallic polycondensation proceeds through a Chain-Growth Polymerization mechanism from an initiator unit derived from the catalyst.
Kevin J. T. Noonan - One of the best experts on this subject based on the ideXlab platform.
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Chain Growth Polymerization of benzotriazole using suzuki miyaura cross coupling and dialkylbiarylphosphine palladium catalysts
ACS Macro Letters, 2020Co-Authors: Michael V. Bautista, Anthony J. Varni, Chia-hua Tsai, Josue Ayusocarrillo, Kevin J. T. NoonanAbstract:Electron-deficient (n-type) conjugated materials are commonly prepared via step-Growth methods with limited control over the molecular weight and molecular weight distribution of the resulting poly...
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Chain-Growth Polymerization of Benzotriazole Using Suzuki–Miyaura Cross-Coupling and Dialkylbiarylphosphine Palladium Catalysts
ACS Macro Letters, 2020Co-Authors: Michael V. Bautista, Anthony J. Varni, Josué Ayuso-carrillo, Chia-hua Tsai, Kevin J. T. NoonanAbstract:Electron-deficient (n-type) conjugated materials are commonly prepared via step-Growth methods with limited control over the molecular weight and molecular weight distribution of the resulting poly...
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A robust nickel catalyst with an unsymmetrical propyl-bridged diphosphine ligand for catalyst-transfer Polymerization
Polymer Journal, 2020Co-Authors: Matthew A. Baker, Anthony J. Varni, Josué Ayuso-carrillo, Martin R. M. Koos, Samantha N. Macmillan, Roberto R. Gil, Kevin J. T. NoonanAbstract:A new nickel diphosphine catalyst was synthesized and evaluated for Suzuki–Miyaura cross-coupling Polymerization. The diphosphine is comprised of two electronically and sterically distinct phosphine donors, a PPh_2 group and a PEt_2 group. The catalyst was employed to bring about controlled Polymerization of a 3-hexylthiophene monomer to afford poly(3-hexylthiophene). The catalyst was particularly effective for bringing about this Polymerization in the presence of excess free ligand. The catalyst resting state was also probed using NMR spectroscopy and an externally initiated catalyst. A new nickel diphosphine catalyst has been synthesized in which the bidentate ligand has two different phosphine donors, a typical PPh_2 group and a stronger σ-donating PEt_2 group. The catalyst was highly effective for the Chain-Growth Polymerization of a 3-alkylthiophene monomer using a Suzuki–Miyaura cross-coupling. The catalyst is particularly effective for this Polymerization in the presence of excess free ligand. The unsymmetrical diphosphine nickel complex reported here represents a new approach to tuning metal-ligand reactivity in the Chain-Growth Polymerization of aromatic monomers. In addition, this new nickel catalyst exhibited increased hydrolytic resistance in the Polymerization as compared to commercially available 1,3-bis(diphenylphosphino)propane nickel dichloride.
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Stille Catalyst-Transfer Polycondensation Using Pd-PEPPSI-IPr for High-Molecular-Weight Regioregular Poly(3-hexylthiophene).
Macromolecular rapid communications, 2015Co-Authors: Yunyan Qiu, Roberto R. Gil, Chia-hua Tsai, Jacob Mohin, Stephanie Tristram-nagle, Tomasz Kowalewski, Kevin J. T. NoonanAbstract:A commercially available palladium N-heterocyclic carbene (Pd-NHC) precatalyst is used to initiate Chain-Growth Polymerization of 2-bromo-3-hexyl-5-trimethylstannylthiophene. The molecular weight of the resultant poly(3-hexylthiophene) can be modulated (7 to 73 kDa, Đ = 1.14 to 1.53) by varying the catalyst concentration. Mass spectrometry data confirm control over the polymer end groups and (1)H NMR spectroscopy reveals that the palladium catalyst is capable of "ring-walking". A linear relationship between Mn and monomer conversion is observed. Atomic force microscopy and X-ray scattering verify the regioregular nature of the resultant polythiophene.
Anne J. Mcneil - One of the best experts on this subject based on the ideXlab platform.
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Accelerating Ni(II) precatalyst initiation using reactive ligands and its impact on Chain-Growth Polymerizations.
Dalton transactions (Cambridge England : 2003), 2013Co-Authors: Ryeon Lee, Jacob W. G. Bloom, Steven E. Wheeler, Anne J. McneilAbstract:Nickel(II) complexes with varying reactive ligands, which were designed to selectively accelerate the initiation rate without influencing the propagation rate in the Chain-Growth Polymerization of π-conjugated monomers, were investigated. Precatalysts with electronically varied reacting groups led to faster initiation rates and narrower molecular weight distributions. Computational studies revealed that the reductive elimination rates are largely modulated by the ability of the two reacting arenes to stabilize the increasing electron density on the catalyst during reductive elimination. Overall, these studies provide insight into a key mechanistic step of cross-coupling reactions (reductive elimination) and highlight the importance of initiation in controlled Chain-Growth Polymerizations.
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Chain Growth Polymerization of aryl grignards initiated by a stabilized nhc pd precatalyst
Macromolecular Rapid Communications, 2012Co-Authors: Zachary J. Bryan, Mitchell L. Smith, Anne J. McneilAbstract:An N-heterocyclic carbene-ligated palladium catalyst was discovered to mediate living, Chain-Growth Polymerizations of both phenylene- and thiophene-based monomers. Polymerization of a fluorene-based monomer, on the other hand, did not proceed through a living, Chain-Growth pathway. Excitingly, block coPolymerizations of phenylene and thiophene proceeded via a Chain-Growth pathway, regardless of the order of monomer addition. Although some Chain termination was observed during these coPolymerizations, this pathway could be minimized when the second monomer was added shortly after consumption of the first monomer. These results suggest that the catalyst resting-state at the end of Polymerization is unstable. As a result, modifications to the NHC-scaffold or the 3-chloropyridine ligand will be necessary to generate an improved catalyst.
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Chain‐Growth Polymerization of Aryl Grignards Initiated by a Stabilized NHC‐Pd Precatalyst
Macromolecular rapid communications, 2012Co-Authors: Zachary J. Bryan, Mitchell L. Smith, Anne J. McneilAbstract:An N-heterocyclic carbene-ligated palladium catalyst was discovered to mediate living, Chain-Growth Polymerizations of both phenylene- and thiophene-based monomers. Polymerization of a fluorene-based monomer, on the other hand, did not proceed through a living, Chain-Growth pathway. Excitingly, block coPolymerizations of phenylene and thiophene proceeded via a Chain-Growth pathway, regardless of the order of monomer addition. Although some Chain termination was observed during these coPolymerizations, this pathway could be minimized when the second monomer was added shortly after consumption of the first monomer. These results suggest that the catalyst resting-state at the end of Polymerization is unstable. As a result, modifications to the NHC-scaffold or the 3-chloropyridine ligand will be necessary to generate an improved catalyst.
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Materials Science and Technology - New Conjugated Polymers and Synthetic Methods
Materials Science and Technology, 2012Co-Authors: Anne J. Mcneil, Erica L. LanniAbstract:The sections in this article are Introduction New Polymers Prepared via Chain-Growth Methods End-Functionalized Polymers All-Conjugated Block Copolymers Mechanism Initial Observations and Mechanistic Proposal Subsequent Mechanistic Studies End-Group Analysis Rate and Spectroscopic Studies Indirect Support for an Intermediate Ni(0)-Polymer π-Complex Remaining Limitations Conclusions and Outlook Keywords: conjugated polymer; nickel; catalysis; Chain-Growth Polymerization; mechanism; cross-coupling
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Evidence for Ligand-Dependent Mechanistic Changes in Nickel-Catalyzed Chain-Growth Polymerizations
Macromolecules, 2010Co-Authors: Erica L. Lanni, Anne J. McneilAbstract:The mechanisms for Ni(dppp)Cl2-catalyzed Chain-Growth Polymerization of 4-bromo-2,5-bis(hexyloxy)phenylmagnesium chloride and 5-bromo-4-hexylthiophen-2-ylmagnesium chloride were investigated. A combination of rate and spectroscopic studies revealed that transmetalation is the rate-determining step of the catalytic cycle for both monomers. 31P NMR spectroscopic studies revealed that a Ni(II)−aryl halide and a Ni(II)−thienyl halide are the catalyst resting states. In addition, LiCl was found to alter the arene Polymerization rates. These results are different than those previously obtained with an alternative catalyst (Ni(dppe)Cl2) and suggest that the ligand has a strong mechanistic influence on the Polymerization.
Akihiro Yokoyama - One of the best experts on this subject based on the ideXlab platform.
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Reaction Control in Condensation Polymerization
Advances in Polymer Science, 2008Co-Authors: Tsutomu Yokozawa, Naomi Ajioka, Akihiro YokoyamaAbstract:Recent progress in the reaction control of condensation Polymerization is described. In the past, the reactions in condensation Polymerization had been improved for the purpose of production of high molecular weight polymer with more convenient methods. In recent years, chemoselective, regioselective, and stereoselective condensation Polymerizations have been developed. Furthermore, it has been revealed that most condensation Polymerizations possess the fundamental tendency to yield cyclic polymers as stable end products when the reactions are optimized for quantitative reaction. When the reactivity of a functional group of a monomer was enhanced after the other functional group of the monomer was reacted, condensation Polymerization of AA and BB monomers afforded polymer with high molecular weight, even under nonstoichiometric conditions, and condensation Polymerization of AB monomer involved a Chain-Growth Polymerization mechanism to yield polymer with narrow molecular weight distribution.
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Chain Growth Polymerization for the synthesis of polyfluorene via suzuki miyaura coupling reaction from an externally added initiator unit
Journal of the American Chemical Society, 2007Co-Authors: Akihiro Yokoyama, Hirofumi Suzuki, Yasuhiro Kubota, Kazuei Ohuchi, Hideyuki Higashimura, Tsutomu YokozawaAbstract:Palladium-catalyzed polycondensation of 2-(7-bromo-9,9-dioctyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1a) with tBu3PPd(Ph)Br (2) via Suzuki−Miyaura coupling reaction was investigated. The Polymerization in a mixture of THF and 2 mol/L aqueous solution of Na2CO3 proceeded smoothly at room temperature and afforded well-defined polyfluorenes with narrow molecular weight distributions. MALDI-TOF mass spectroscopy showed that the obtained polymers have a phenyl group at one end. The relationships of conversion to number-average molecular weight (Mn) and feed ratio to Mn were linear. These results demonstrate that this organometallic polycondensation proceeds through a Chain-Growth Polymerization mechanism from an initiator unit derived from the catalyst.
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Chain-Growth Polymerization for the Synthesis of Polyfluorene via Suzuki−Miyaura Coupling Reaction from an Externally Added Initiator Unit
Journal of the American Chemical Society, 2007Co-Authors: Akihiro Yokoyama, Hirofumi Suzuki, Yasuhiro Kubota, Kazuei Ohuchi, Hideyuki Higashimura, Tsutomu YokozawaAbstract:Palladium-catalyzed polycondensation of 2-(7-bromo-9,9-dioctyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1a) with tBu3PPd(Ph)Br (2) via Suzuki−Miyaura coupling reaction was investigated. The Polymerization in a mixture of THF and 2 mol/L aqueous solution of Na2CO3 proceeded smoothly at room temperature and afforded well-defined polyfluorenes with narrow molecular weight distributions. MALDI-TOF mass spectroscopy showed that the obtained polymers have a phenyl group at one end. The relationships of conversion to number-average molecular weight (Mn) and feed ratio to Mn were linear. These results demonstrate that this organometallic polycondensation proceeds through a Chain-Growth Polymerization mechanism from an initiator unit derived from the catalyst.
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Converting step-Growth to Chain-Growth condensation Polymerization
Macromolecules, 2007Co-Authors: Akihiro Yokoyama, Tsutomu YokozawaAbstract:The development and applications of Chain-Growth condensation Polymerization are reviewed. Well-defined aromatic polyamides, polyesters, and polyethers have been synthesized via substituent effect-assisted Chain-Growth condensation Polymerization, in which the polymer propagating ends are more reactive than the monomers due to resonance or inductive effects between the functional groups of the terminal monomer units. Chain-Growth condensation Polymerization for the synthesis of aromatic polyamides has been applied to the construction of well-defined block copolymers and star-shaped polymers. Nickel-catalyzed condensation Polymerization of 5-metalated 2-halothiophene has been found to proceed in a Chain-Growth Polymerization manner. Detailed investigations revealed that this Polymerization is a catalyst-transfer condensation Polymerization, in which the Chain-Growth nature is attributable to intramolecular catalyst transfer. Phase-transfer Polymerization in a solid−solution biphasic system, in which the mo...
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Synthesis of Block Copolymers Containing Well-Defined Condensation Polymers and Possible Application to Novel Thermoplastic Elastomers
NIPPON GOMU KYOKAISHI, 2003Co-Authors: Tsutomu Yokozawa, Akihiro YokoyamaAbstract:Thermoplastic elastomers containing condensation polymers have been produced as generally multiblock copolymers, not di- or triblock copolymers, because polycondensation proceeds in a step-Growth Polymerization manner, not in a Chain-Growth Polymerization manner like living Polymerization. We have recently developed novel polycondensation that propagates from an initiator in a Chain-Growth manner (Chain-Growth polycondensation) to yield condensation polymers with defined molecular weights and low polydispersities. This polycondensation method will open to an access to new thermoplastic elastomers made of triblock and star block copolymers containing well-defined condensation polymers as block units. Herein we describe the polycondensation for well-defined aromatic polyamides as an example of Chain-Growth polycondensation and the synthesis of block copolymers and star block copolymers, which consist of condensation polymers and general polymers such as polystylene and poly(ethylene glycol). Furthermore, its application to the synthesis of novel thermoplastic elastomers is also discussed.
Guy Koeckelberghs - One of the best experts on this subject based on the ideXlab platform.
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study of the controlled Chain Growth Polymerization of poly 3 6 phenanthrene
Journal of Polymer Science Part A, 2013Co-Authors: Michiel Verswyvel, Julien De Winter, Pascal Gerbaux, Charly Hoebers, Guy KoeckelberghsAbstract:Acquiring control on the synthesis of the different classes of π-conjugated polymers (CPs) is one of the main goals polymer chemists pursue nowadays. CPs are used because of their promising applications in electronic devices, e.g. organic solar cells, organic LED’s, supercapacitors, biosensors, etc. Their molecular architecture and structure are playing a dominant role in their performance. Building predetermined molecular structures with low Đ values was the challenge in the past and will continue to be so in the future. The major breakthrough was the discovery of the Kumada catalyst-transfer Polymerization of poly(3-alkylthiophene) with Ni(dppp)Cl2 as a catalyst by the research groups of Yokozawa and McCullough in 2004. A controlled Chain-Growth Polymerization mechanism was demonstrated. Shortly after, also other CPs were polymerized in a Chain Growth manner using the same or other catalysts: poly(thiophenes) with Pd(Ruphos), Pd(Bu3), 9 Ni(α-diimine) or Pd(NHC), poly(fluorenes) with Ni(acac)/dppp, Pd(PBu3), 14 Pd(Ruphos) or Pd(NHC), poly(p-phenylene) with Pd(PBu3), 15 Ni(dppe), or Pd(NHC), poly(p-phenylene ethynylene) with Pd(PBu3), 18 poly(pyrrole) with Ni(dppe), etc ((NHC) = N-heterocyclic carbene, (dppp) = diphenylphosphinopropane, (dppe) = diphenylphosphinoethane). Initiation of these polymers can happen in two ways. The catalyst salt can be added and, after an initial reduction, the initiating moiety is formed in situ. Alternatively, or a premade external initiator can be used. The latter approach allows the incorporation of functional end ABSTRACT
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Study of the controlled Chain‐Growth Polymerization of poly(3,6‐phenanthrene)
Journal of Polymer Science Part A: Polymer Chemistry, 2013Co-Authors: Michiel Verswyvel, Julien De Winter, Pascal Gerbaux, Charly Hoebers, Guy KoeckelberghsAbstract:Acquiring control on the synthesis of the different classes of π-conjugated polymers (CPs) is one of the main goals polymer chemists pursue nowadays. CPs are used because of their promising applications in electronic devices, e.g. organic solar cells, organic LED’s, supercapacitors, biosensors, etc. Their molecular architecture and structure are playing a dominant role in their performance. Building predetermined molecular structures with low Đ values was the challenge in the past and will continue to be so in the future. The major breakthrough was the discovery of the Kumada catalyst-transfer Polymerization of poly(3-alkylthiophene) with Ni(dppp)Cl2 as a catalyst by the research groups of Yokozawa and McCullough in 2004. A controlled Chain-Growth Polymerization mechanism was demonstrated. Shortly after, also other CPs were polymerized in a Chain Growth manner using the same or other catalysts: poly(thiophenes) with Pd(Ruphos), Pd(Bu3), 9 Ni(α-diimine) or Pd(NHC), poly(fluorenes) with Ni(acac)/dppp, Pd(PBu3), 14 Pd(Ruphos) or Pd(NHC), poly(p-phenylene) with Pd(PBu3), 15 Ni(dppe), or Pd(NHC), poly(p-phenylene ethynylene) with Pd(PBu3), 18 poly(pyrrole) with Ni(dppe), etc ((NHC) = N-heterocyclic carbene, (dppp) = diphenylphosphinopropane, (dppe) = diphenylphosphinoethane). Initiation of these polymers can happen in two ways. The catalyst salt can be added and, after an initial reduction, the initiating moiety is formed in situ. Alternatively, or a premade external initiator can be used. The latter approach allows the incorporation of functional end ABSTRACT
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development of a universal Chain Growth Polymerization protocol of conjugated polymers toward a variety of all conjugated block copolymers
Journal of Polymer Science Part A, 2011Co-Authors: Michiel Verswyvel, Thierry Verbiest, Pieter Verstappen, Lieven De Cremer, Guy KoeckelberghsAbstract:This manuscript reports a universal Chain-Growth Polymerization protocol for conjugated polymers. Herein, the Pd-based catalyst moiety dissociates from the growing active center into the solution and therefore, the controlled Chain-Growth character is not relying on any specific, system-related complexation, as is the case in Polymerization methods reported before. This makes the protocol applicable on a broad range of monomers and, furthermore, also allows an easy one-pot synthesis of block-copolymers by successive monomer addition. A Chain-Growth
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Development of a universal Chain‐Growth Polymerization protocol of conjugated polymers: Toward a variety of all‐conjugated block‐copolymers
Journal of Polymer Science Part A: Polymer Chemistry, 2011Co-Authors: Michiel Verswyvel, Thierry Verbiest, Pieter Verstappen, Lieven De Cremer, Guy KoeckelberghsAbstract:This manuscript reports a universal Chain-Growth Polymerization protocol for conjugated polymers. Herein, the Pd-based catalyst moiety dissociates from the growing active center into the solution and therefore, the controlled Chain-Growth character is not relying on any specific, system-related complexation, as is the case in Polymerization methods reported before. This makes the protocol applicable on a broad range of monomers and, furthermore, also allows an easy one-pot synthesis of block-copolymers by successive monomer addition. A Chain-Growth
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Quest for a universal controlled Chain-Growth Polymerization protocol: Toward a variety of all-conjugated block-copolymers
2011Co-Authors: Michiel Verswyvel, Thierry Verbiest, Pieter Verstappen, Lieven De Cremer, Guy KoeckelberghsAbstract:Introduction Conjugated polymers (CPs) remain intensively studied materials as they hold promise as active layers in applications in the field of molecular electronics (solar cells, etc.). The realization of these current and future materials increasingly requires tailor–made polymers. A major break-through in this respect was realized by the groups of McCullough and Yokozawa by demonstrating the controlled Chain-Growth nature of the Ni(dppp)Cl2 (dppp = 1,3-bis(diphenylphosphino)propane) initiated Polymerization of P3ATs. The actual Polymerization reaction is a Kumada coupling of 3-alkyl-2-bromo-5chloromagnesiothiophenes. Also other monomers have been polymerized in a Chain-Growth, sometimes to a certain extent controlled, mechanism. Apart from the Ni(dppp)(or Ni(dppe); dppe = 1,2-bis(diphenylphosphino)ethane)mediated Polymerization of CPs, Yokozawa reported the controlled Polymerization of poly(fluorene)s, poly(phenylene)s and poly(thiophene)s from their monobromo-monoboronic ester-functionalized monomers using Ph(Pd(t-Bu))Br as an initiator. This paper reports an alternative, more general Chain-Growth Polymerization protocol.