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Krzysztof Matyjaszewski - One of the best experts on this subject based on the ideXlab platform.

  • atom transfer radical polymerization of acrylic and methacrylic acids preparation of acidic polymers with various architectures
    ACS Macro Letters, 2020
    Co-Authors: Armando Gennaro, Marco Fantin, Francesca Lorandi, Abdirisak Ahmed Isse, Yi Wang, Krzysztof Matyjaszewski
    Abstract:

    The preparation of poly(acrylic acid) (PAA) with tailored architecture and morphology is important for the design of advanced polymer materials. Cu-catalyzed atom transfer radical polymerization (A...

  • iron catalysts in atom transfer radical polymerization
    Molecules, 2020
    Co-Authors: Sajjad Dadashisilab, Krzysztof Matyjaszewski
    Abstract:

    Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-based monomers by iron catalysts still remains a challenge. In this paper, we review the fundamentals and recent advances of iron-catalyzed ATRP focusing on development of ligands, catalyst design, and techniques used for iron catalysis in ATRP.

  • translating surface initiated atom transfer radical polymerization into technology the mechanism of cu0 mediated si atrp under environmental conditions
    ACS Macro Letters, 2019
    Co-Authors: Wenqing Yan, Krzysztof Matyjaszewski, Marco Fantin, Nicholas D Spencer, Edmondo M Benetti
    Abstract:

    The exceptional features of Cu0-mediated surface-initiated atom transfer radical polymerization (Cu0 SI-ATRP), and its potential for implementation in technologically relevant surface functionaliza...

  • solution processable liquid metal nanodroplets by surface initiated atom transfer radical polymerization
    Nature Nanotechnology, 2019
    Co-Authors: Jiajun Yan, Mohammad H Malakooti, Zongyu Wang, Navid Kazem, Chengfeng Pan, Michael R Bockstaller, Carmel Majidi, Krzysztof Matyjaszewski
    Abstract:

    Eutectic gallium indium (EGaIn) is a liquid metal alloy at room temperature. EGaIn microdroplets can be incorporated into elastomers to fabricate highly stretchable, mechanically robust, soft multifunctional composites with high thermal stability1 and electrical conductivity2–4 that are suitable for applications in soft robotics and self-healing electronics5–7. However, the current methods of preparation rely on mechanical mixing, which may lead to irregularly shaped micrometre-sized droplets and an anisotropic distribution of properties8. Therefore, procedures for the stabilization of sub-micrometre-sized droplets of EGaIn and compatibilization in polymer matrices and solvents have attracted significant attention9–12. Here we report the synthesis of EGaIn nanodroplets stabilized by polymeric ligand encapsulation. We use a surface-initiated atom transfer radical polymerization initiator to covalently functionalize the oxide layer on the surface of the EGaIn nanodroplets13 with poly(methyl methacrylate) (PMMA), poly(n-butyl acrylate) (PBMA), poly(2-dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(n-butyl acrylate-block-methyl methacrylate) (PBA-b-PMMA). These nanodroplets are stable in organic solvents, in water or in polymer matrices up to 50 wt% concentration, enabling direct solution-casting into flexible hybrid materials. The liquid metal can be recovered from dispersion by acid treatment. The nanodroplets show good mechanical, thermal and optical properties, with a remarkable suppression of crystallization and melting temperatures (down to −80 °C from 15 °C). Eutectic Ga-In droplets can be functionalized with various polymers and co-polymers using atom transfer radical polymerization. The droplets are ready for direct solution processing to form liquid-metal nanocomposites for potential applications in soft robotics.

  • biocatalytic oxygen fueled atom transfer radical polymerization
    Angewandte Chemie, 2018
    Co-Authors: Alan E Enciso, Sushil Lathwal, Mateusz Olszewski, Zhenhua Wang, Subha R Das, Alan J Russell, Krzysztof Matyjaszewski
    Abstract:

    Atom transfer radical polymerization (ATRP) can be carried out in a flask completely open to air using a biocatalytic system composed of glucose oxidase (GOx) and horseradish peroxidase (HRP) with an active copper catalyst complex. Nanomolar concentrations of the enzymes and ppm amounts of Cu provided excellent control over the polymerization of oligo(ethylene oxide) methyl ether methacrylate (OEOMA500 ), generating polymers with high molecular weight (Mn >70 000) and low dispersities (1.13≤Đ≤1.27) in less than an hour. The continuous oxygen supply was necessary for the generation of radicals and polymer chain growth as demonstrated by temporal control and by inducing hypoxic conditions. In addition, the enzymatic cascade polymerization triggered by oxygen was used for a protein and DNA functionalized with initiators to form protein-b-POEOMA and DNA-b-POEOMA bioconjugates, respectively.

Nicolay V Tsarevsky - One of the best experts on this subject based on the ideXlab platform.

  • epoxides as reducing agents for low catalyst concentration atom transfer radical polymerization
    Macromolecular Rapid Communications, 2014
    Co-Authors: Shannon R Woodruff, Brad J Davis, Nicolay V Tsarevsky
    Abstract:

    Activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) conditions utilizing a low concentration of catalyst are successfully applied for the preparation of well-defined poly(glycidyl methacrylate) without the addition of external reducing agents. The living character of polymerization is evidenced by successful chain extensions with methyl methacrylate and methyl acrylate, again, in the absence of additional reducing agents, yielding block copolymers. The epoxide groups in glycidyl methacrylate or the corresponding polymer can serve as an intrinsic reducing agent to continuously regenerate the Cu(I) -based ATRP activator from the Cu(II) halide complex present in the systems. The reactivity of various epoxides in the reduction of the Cu(II) Br2 complex of tris(2-pyridylmethyl)amine is compared.

  • low catalyst concentration atom transfer radical polymerization of a phosphonium salt type monomer
    Polymer Chemistry, 2012
    Co-Authors: Yannick Borguet, Nicolay V Tsarevsky
    Abstract:

    Polymeric phosphonium salts are an important class of polyelectrolytes that are currently gaining increasing interest due to their solution properties and reactivity. The successful controlled/living radical polymerization of a phosphonium salt-type monomer, 4-vinylbenzyltriphenylphosphonium tetrafluoroborate (4VBTPPBF4), under initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) conditions employing a low concentration of catalyst is reported. After optimization of the reaction conditions, high monomer conversions to the polymeric phosphonium salt, poly4VBTPPBF4, were reached with very good polymerization control. The living character of the polymerizations was further evidenced via chain extension experiments that yielded either higher molecular weight homopolymers or block copolymers. It is also shown that poly4VBTPPBF4 can be efficiently converted to linear poly(4-vinylstyrene) using the Wittig olefination reaction.

  • nanostructured functional materials prepared by atom transfer radical polymerization
    Nature Chemistry, 2009
    Co-Authors: Krzysztof Matyjaszewski, Nicolay V Tsarevsky
    Abstract:

    The simplicity and broad applicabilty of atom transfer radical polymerization make it a rapidly developing area of synthetic polymer chemistry. Here, the fundamentals of the technique are discussed, along with how it can be used to synthesize macromolecules with controlled molecular architecture, and how their self-assembly can create nanostructured functional materials.

  • electron transfer reactions relevant to atom transfer radical polymerization
    Journal of Organometallic Chemistry, 2007
    Co-Authors: Nicolay V Tsarevsky, Wade A Braunecker, Krzysztof Matyjaszewski
    Abstract:

    The continuous development of more active and stable catalysts in atom transfer radical polymerization (ATRP) has increasingly required a thorough knowledge of concurrent electron transfer reactions that can affect catalyst performance. Special attention is provided in this short review to such processes, including disproportionation, most pronounced in Cu-mediated ATRP, the reduction of radicals to carbanions or oxidation to carbocations, and radical coordination to the metal catalyst resulting in the interplay of controlled radical polymerization mechanisms.

  • highly active copper based catalyst for atom transfer radical polymerization
    Journal of the American Chemical Society, 2006
    Co-Authors: Huadong Tang, Nicolay V Tsarevsky, Wade A Braunecker, Navamoney Arulsamy, Maciej Radosz, Youqing Shen, Wei Tang, Krzysztof Matyjaszewski
    Abstract:

    Atom transfer radical polymerization (ATRP) generally requires a catalyst/initiator molar ratio of 0.1 to 1 and catalyst/monomer molar ratio of 0.001 to 0.01 (i.e., catalyst concentration:  1000−10 000 ppm versus monomer). Herein, we report a new copper-based complex CuBr/N,N,N‘,N‘-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) as a versatile and highly active catalyst for acrylic, methacrylic, and styrenic monomers. The catalyst mediated ATRP at a catalyst/initiator molar ratio of 0.005 and produced polymers with well-controlled molecular weights and low polydispersities. ATRP occurred even at a catalyst/initiator molar ratio as low as 0.001 with copper concentration in the produced polymers as low as 6−8 ppm (catalyst/monomer molar ratio = 10-5). The catalyst structures were studied by X-ray diffraction and NMR spectroscopy. The activator CuIBr/TPEN existed in solution as binuclear and mononuclear complexes in equilibrium but as a binuclear complex in its single crystals. The deactivator CuIIBr2/TPEN c...

Marco Fantin - One of the best experts on this subject based on the ideXlab platform.

Abdirisak Ahmed Isse - One of the best experts on this subject based on the ideXlab platform.

  • atom transfer radical polymerization of acrylic and methacrylic acids preparation of acidic polymers with various architectures
    ACS Macro Letters, 2020
    Co-Authors: Armando Gennaro, Marco Fantin, Francesca Lorandi, Abdirisak Ahmed Isse, Yi Wang, Krzysztof Matyjaszewski
    Abstract:

    The preparation of poly(acrylic acid) (PAA) with tailored architecture and morphology is important for the design of advanced polymer materials. Cu-catalyzed atom transfer radical polymerization (A...

  • impact of organometallic intermediates on copper catalyzed atom transfer radical polymerization
    Macromolecules, 2019
    Co-Authors: Marco Fantin, Francesca Lorandi, Thomas G Ribelli, Grzegorz Szczepaniak, Alan E Enciso, Christophe Fliedel, Lucas Thevenin, Abdirisak Ahmed Isse, Rinaldo Poli
    Abstract:

    In atom transfer radical polymerization (ATRP), radicals (R•) can react with CuI/L catalysts forming organometallic complexes, R–CuII/L (L = N-based ligand). R–CuII/L favors additional catalyzed ra...

  • electron transfer reactions in atom transfer radical polymerization
    Synthesis, 2017
    Co-Authors: Marco Fantin, Armando Gennaro, Francesca Lorandi, Abdirisak Ahmed Isse, Krzysztof Matyjaszewski
    Abstract:

    Electrochemistry may seem an outsider to the field of polymer science and controlled radical polymerization. Nevertheless, several electrochemical methods have been used to determine the mechanism of atom transfer radical polymerization (ATRP), using both a thermodynamic and a kinetic approach. Indeed, electron transfer reactions involving the metal catalyst, initiator/dormant species, and propagating radicals play a crucial role in ATRP. In this mini-review, electrochemical properties of ATRP catalysts and initiators are discussed, together with the mechanism of the atom and electron transfer in ATRP. 1 Introduction 2 Thermodynamic and Electrochemical Properties of ATRP Catalysts 3 Thermodynamic and Electrochemical Properties of Alkyl Halides and Alkyl Radicals 4 Atom Transfer from an Electrochemical and Thermodynamic Standpoint 5 Mechanism of Electron Transfer in ATRP 6 Electroanalytical Techniques for the Kinetics of ATRP Activation 7 Electrochemically Mediated ATRP 8 Conclusions

  • atom transfer radical polymerization of methacrylic acid a won challenge
    Journal of the American Chemical Society, 2016
    Co-Authors: Marco Fantin, Armando Gennaro, Abdirisak Ahmed Isse, Alfonso Venzo, Krzysztof Matyjaszewski
    Abstract:

    Polymerization of acidic monomers is one of the biggest challenges for atom transfer radical polymerization (ATRP). An intramolecular cyclization reaction leading to the loss of the C–X chain-end functionality was found to be the main reason for the partial termination of the growing polymer chains. Three approaches were used to overcome this problem: using Cl as the chain-end halogen, lowering the pH (to 0.9), and increasing polymerization rate. Methacrylic acid (MAA) was polymerized by both electrochemically mediated ATRP and supplemental activator and reducing agent ATRP up to high conversion (>90%), in t ≤ 4 h at 25 °C, using inexpensive and nontoxic reagents (NaCl, diluted HCl, water). Control over molecular weight (MW) dispersity was satisfactory, and MWs were in agreement with theoretical values. The “livingness” of the process was confirmed by an electrochemical switch, used to repeatedly and periodically deactivate/reactivate growing chains.

  • mechanism of photoinduced metal free atom transfer radical polymerization experimental and computational studies
    Journal of the American Chemical Society, 2016
    Co-Authors: Xiangcheng Pan, Armando Gennaro, Marco Fantin, Abdirisak Ahmed Isse, Cheng Fang, Nikhil Malhotra, Linda A Peteanu, Peng Liu, Krzysztof Matyjaszewski
    Abstract:

    Photoinduced metal-free atom transfer radical polymerization (ATRP) of methyl methacrylate was investigated using several phenothiazine derivatives and other related compounds as photoredox catalysts. The experiments show that all selected catalysts can be involved in the activation step, but not all of them participated efficiently in the deactivation step. The redox properties and the stability of radical cations derived from the catalysts were evaluated by cyclic voltammetry. Laser flash photolysis (LFP) was used to determine the lifetime and activity of photoexcited catalysts. Kinetic analysis of the activation reaction according to dissociative electron-transfer (DET) theory suggests that the activation occurs only with an excited state of catalyst. Density functional theory (DFT) calculations revealed the structures and stabilities of the radical cation intermediates as well as the reaction energy profiles of deactivation pathways with different photoredox catalysts. Both experiments and calculation...

Armando Gennaro - One of the best experts on this subject based on the ideXlab platform.

  • atom transfer radical polymerization of acrylic and methacrylic acids preparation of acidic polymers with various architectures
    ACS Macro Letters, 2020
    Co-Authors: Armando Gennaro, Marco Fantin, Francesca Lorandi, Abdirisak Ahmed Isse, Yi Wang, Krzysztof Matyjaszewski
    Abstract:

    The preparation of poly(acrylic acid) (PAA) with tailored architecture and morphology is important for the design of advanced polymer materials. Cu-catalyzed atom transfer radical polymerization (A...

  • electron transfer reactions in atom transfer radical polymerization
    Synthesis, 2017
    Co-Authors: Marco Fantin, Armando Gennaro, Francesca Lorandi, Abdirisak Ahmed Isse, Krzysztof Matyjaszewski
    Abstract:

    Electrochemistry may seem an outsider to the field of polymer science and controlled radical polymerization. Nevertheless, several electrochemical methods have been used to determine the mechanism of atom transfer radical polymerization (ATRP), using both a thermodynamic and a kinetic approach. Indeed, electron transfer reactions involving the metal catalyst, initiator/dormant species, and propagating radicals play a crucial role in ATRP. In this mini-review, electrochemical properties of ATRP catalysts and initiators are discussed, together with the mechanism of the atom and electron transfer in ATRP. 1 Introduction 2 Thermodynamic and Electrochemical Properties of ATRP Catalysts 3 Thermodynamic and Electrochemical Properties of Alkyl Halides and Alkyl Radicals 4 Atom Transfer from an Electrochemical and Thermodynamic Standpoint 5 Mechanism of Electron Transfer in ATRP 6 Electroanalytical Techniques for the Kinetics of ATRP Activation 7 Electrochemically Mediated ATRP 8 Conclusions

  • atom transfer radical polymerization of methacrylic acid a won challenge
    Journal of the American Chemical Society, 2016
    Co-Authors: Marco Fantin, Armando Gennaro, Abdirisak Ahmed Isse, Alfonso Venzo, Krzysztof Matyjaszewski
    Abstract:

    Polymerization of acidic monomers is one of the biggest challenges for atom transfer radical polymerization (ATRP). An intramolecular cyclization reaction leading to the loss of the C–X chain-end functionality was found to be the main reason for the partial termination of the growing polymer chains. Three approaches were used to overcome this problem: using Cl as the chain-end halogen, lowering the pH (to 0.9), and increasing polymerization rate. Methacrylic acid (MAA) was polymerized by both electrochemically mediated ATRP and supplemental activator and reducing agent ATRP up to high conversion (>90%), in t ≤ 4 h at 25 °C, using inexpensive and nontoxic reagents (NaCl, diluted HCl, water). Control over molecular weight (MW) dispersity was satisfactory, and MWs were in agreement with theoretical values. The “livingness” of the process was confirmed by an electrochemical switch, used to repeatedly and periodically deactivate/reactivate growing chains.

  • mechanism of photoinduced metal free atom transfer radical polymerization experimental and computational studies
    Journal of the American Chemical Society, 2016
    Co-Authors: Xiangcheng Pan, Armando Gennaro, Marco Fantin, Abdirisak Ahmed Isse, Cheng Fang, Nikhil Malhotra, Linda A Peteanu, Peng Liu, Krzysztof Matyjaszewski
    Abstract:

    Photoinduced metal-free atom transfer radical polymerization (ATRP) of methyl methacrylate was investigated using several phenothiazine derivatives and other related compounds as photoredox catalysts. The experiments show that all selected catalysts can be involved in the activation step, but not all of them participated efficiently in the deactivation step. The redox properties and the stability of radical cations derived from the catalysts were evaluated by cyclic voltammetry. Laser flash photolysis (LFP) was used to determine the lifetime and activity of photoexcited catalysts. Kinetic analysis of the activation reaction according to dissociative electron-transfer (DET) theory suggests that the activation occurs only with an excited state of catalyst. Density functional theory (DFT) calculations revealed the structures and stabilities of the radical cation intermediates as well as the reaction energy profiles of deactivation pathways with different photoredox catalysts. Both experiments and calculation...

  • simplified electrochemically mediated atom transfer radical polymerization using a sacrificial anode
    Angewandte Chemie, 2015
    Co-Authors: Sangwoo Park, Pawel Chmielarz, Armando Gennaro, Krzysztof Matyjaszewski
    Abstract:

    Simplification of electrochemically mediated atom transfer radical polymerization was achieved efficiently under either potentiostatic or galvanostatic conditions using an aluminum wire sacrificial anode (seATRP) immersed directly into the reaction flask without separating the counter electrode. seATRP polymerizations were carried out under different applied potentials, Eapps=E1/2, Epc, Epc −40 mV, and Epc −80 mV. As the rate of polymerization (Rp) can be modulated by applying different Eapp potentials, more reducing conditions resulted in faster Rp. The polymerization results showed similar narrow molecular-weight distribution throughout the reactions, similar to results observed for n-butyl acrylate (BA) polymerization under conventional eATRP. High-molecular-weight PBA and diblock copolymers were synthesized by seATRP with more than 90 % monomer conversion. Furthermore, galvanostatic conditions were developed for synthesizing PBA with the two-electrode system.