Initiators atom transfer mediated polymerizations

Schematic diagram illustrating the process of immobilization of trichlorosilane coupling agent on the ITO surface, surface-initiated ATRP of GMA from the ITO-Cl surface to produce the inner block, followed by block copolymer of FMMA and the coupling of GOD to the epoxide groups of the P(GMA) (scheme 1). In scheme 2, P(FMMA) is first grafted from the ITO-Gl surface, and the P(GM A) segment is then grafted as the outer block of the copolymer. (Reproduced from Zhang et al. 2010. Enzyme-mediated amperometric biosensors prepared via successive surface-initiated atom-transfer radical polymerization. Biosensors Bioelectronics 25 (5) 1102-1108, with permission from Elsevier.)...

Zhang, Z. B., S. J. Yuan, X. L. Zhu, K. G. Neoh, and E. T. Kang. 2010. Enzyme-mediated amperometric biosensors prepared via successive surface-initiated atom-transfer radical polymerization. 

ORl OX w di-Miutyl peroxyoxalalc deactivation by reversible chain transfer and bioinolecular aclivaiion 456 atom transfer radical polymerization 7, 250, 456,457, 458,461.486-98 deactivation by reversible coupling and untmolecular activation 455-6, 457-86 carbon-centered radical-mediated poly nierizaiion 467-70 initiators, inferlers and iriiters 457-8 metal complex-mediated radical polymerization 484... 

The last decades have witnessed the emergence of new living Vcontrolled polymerizations based on radical chemistry [81, 82]. Two main approaches have been investigated the first involves mediation of the free radical process by stable nitroxyl radicals, such as TEMPO while the second relies upon a Kharash-type reaction mediated by metal complexes such as copper(I) bromide ligated with 2,2 -bipyridine. In the latter case, the polymerization is initiated by alkyl halides or arenesulfonyl halides. Nitroxide-based initiators are efficient for styrene and styrene derivatives, while the metal-mediated polymerization system, the so called ATRP (Atom Transfer Radical Polymerization) seems the most robust since it can be successfully applied to the living Vcontrolled polymerization of styrenes, acrylates, methacrylates, acrylonitrile, and isobutene. Significantly, both TEMPO and metal-mediated polymerization systems allow molec-... 

In this review, synthesis of block copolymer brushes will be Hmited to the grafting-from method. Hussemann and coworkers [35] were one of the first groups to report copolymer brushes. They prepared the brushes on siUcate substrates using surface-initiated TEMPO-mediated radical polymerization. However, the copolymer brushes were not diblock copolymer brushes in a strict definition. The first block was PS, while the second block was a 1 1 random copolymer of styrene/MMA. Another early report was that of Maty-jaszewski and coworkers [36] who reported the synthesis of poly(styrene-h-ferf-butyl acrylate) brushes by atom transfer radical polymerization (ATRP). 

The synthesis of mixed peroxides formed from /-butyl hydroperoxide and carbon-centred radicals has been studied. The reactions were strongly effected by solvents as well as catalytic amounts of Cun/Fem. The kinetic data suggest that the conditions for the Ingold-Fischer persistent radical effect are fulfilled in these cases.191 The use of Cu /Cu" redox couples in mediating living radical polymerization continues to be of interest. The kinetics of atom-transfer radical polymerization (ATRP) of styrene with CuBr and bipyridine have been investigated. The polymer reactions were found to be first order with respect to monomer, initiator and CuBr concentration, with the optimum CuBr Bipy ratio found to be 2 1.192 In related work using CuBr-A-pentyl-2-... 

Fe(III) species can also be employed in a so-called reverse or alternative atom-transfer radical polymerization (section II.B.9). A mixture of FeCl3 and PPh3 can mediate a controlled polymerization of MMA in the presence of AIBN to give similarly narrow MWDs MJMn = 1.1—1.3).80 An ammonium halide such as />Bu4NBr can be employed in place of PPh3 as a ligand for FeBr3 in the AIBN-initiated radical polymerization.74... 

Controlled Radical Polymerization (CRP) is the most recently developed polymerization technology for the preparation of well defined functional materials. Three recently developed CRP processes are based upon forming a dynamic equilibrium between active and dormant species that provides a slower more controlled chain growth than conventional radical polymerization. Nitroxide Mediated Polymerization (NMP), Atom Transfer Radical Polymerization (ATRP) and Reversible Addition Fragmentation Transfer (RAFT) have been developed, and improved, over the past two decades, to provide control over radical polymerization processes. This chapter discusses the patents issued on ATRP initiation procedures, new functional materials prepared by CRP, and discusses recent improvements in all three CRP processes. However the ultimate measure of success for any CRP system is the preparation of conunercially viable products using acceptable economical manufacturing procedures. 

Controlled/ living radical polymerization (CLRP) processes are well-established synthetic routes for the production of well-defined, low-molecular weight-dispersity polymers [99]. The types of CLRP processes (initiator-transfer agent-terminator (INIFERTER), atom transfer radical polymerization (ATRP), nitroxide-mediated radical (NMRP) polymerization, reversible addition-fragmentation transfer (RAFT)) and their characteristics are described in Section 3.8 of Chapter 3 and in Section 14.8 of Chapter 14. 

Atom transfer radical polymerization (ATRP) reactions mediated by transition metals have also garnered interest.Essentially, ATRP reactions are similar to traditional free-radical polymerization reactions in that they can be described by initiation, propagation, and chain-transfer steps involving carbon radicals. Transition metals mediate this process via redox processes (M => and promoting chain transfer by donation of a... 

Controlled radical polymerization techniques are suitable for synthesizing polymers with a high level of architectural control. Notably, they not only allow a copolymerization with functional monomers (as shown previously for free-radical polymerization), but also a simple functionalization of the chain end by the initiator. Miniemulsion systems were found suitable for conducting controlled radical polymerizations [58-61], including atom transfer radical polymerization (ATRP), RAFT, degenerative iodine transfer [58], and nitroxide-mediated polymerization (NMP). Recently, the details of ATRP in miniemulsion were described in several reviews [62, 63], while the kinetics of RAFT polymerization in miniemulsion was discussed by Tobita [64]. Consequently, no detailed descriptions of the process wiU be provided at this point. 

In terms of the atom transfer reversible activation mechanism, the most actively studied method is atom transfer radical polymerization (ATRP), which was first demonstrated in 1995 [41—43]. ATRP reactions use a halogenated initiator (e.g. alkyl halide) to start the polymerization and the halide becomes the removable controlling agent on the polymer chain endgroup. A transition metal complex is present in the formulation to mediate the removal of the halide radical from the polymer chain. The general atom transfer reversible activation scheme shown previously can be represented in more detail for ATRP by the reaction shown in Scheme 13.8. 

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