Activators generated by electron transfer ATRP

Scheme 24.2 Self-condensing vinyl polymerization [AGET (activators generated by electron transfer) ATRP] of 4-chloromethylstyrene.

Activator generated by electron transfer ATRP AGETATRP... 

Poly(n-butyl acrylate) brushes were synthesized by activators generated by electron transfer (AGET) ATRP of BA from 2-bromoisobutyrate functionalized silica particles in miniemulsion imder conditions similar to those reported previously, BA Si02-Br CuBr2 BPMODA ascorbic acid = 600 1 0.5 0.5 ... 

Better results again were obtained using a conventional ATRP initiation and in sHu catalyst (CuBri/BPMODA) reduction by AGET (Activator Generated by Electron Transfer)." In this case water soluble ascorbic acid was used as the reducing agent and it was presumed that catalyst reduction occurs in the aqueous phase. 

SR NI evolved into activators generated by electron transfer (AGET) where an ATRP initiator is added to the reaction as a separate compound along with the higher oxidation state catalyst precursor for an active ATRP catalyst complex. The... 

Figure 20 Activator generated by electron transfer (AGET) ATRP. Activating species Cu Br/L is generated in situ by reduction of Cu"Br/L.

Initiated ATRP, and ATRP with Activators Generated by Electron Transfer... 

Whenever vinyl monomers are electropolymerized, two situations must be distinguished depending on whether the vinyl monomer is the precursor of the initiating species or not. Either the polymerization is directly initiated by the activated monomer or the initiation is indirect whenever the active species (radical, anion, or cation) is generated by a compound other than the monomer (conducting salt, solvent, or properly selected additives). Besides these electroinitiated polymerization processes, a very recent report also demonstrated that electrochemistry is a valuable tool to mediate atom transfer radical polymerization (ATRP). Indeed, an externally applied electrochemical potential can activate the copper catalyst by a one-electron reduction of an irutially added air-stable cupric species (Cu /ligand) allowing... 

Atom-transfer radical polymerization (ATRP) is another example of a CRP technique. The general mechanism for ATRP is shown in Scheme 3. The radicals, or the active species, are generated through a reversible redox process catalyzed by a transition metal complex (Mt"-Y/ligand, where Y may be another ligand or the cotmterion), which undergoes a one electron oxidation followed by abstraction of a halogen atom, X, from a dormant species, R-X. Several transition metals can catalyze the process, but Cu(I) complexes have received the most attention [141]. 

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