Formation and Possible
Reactions of Organometallic
Intermediates with Active Copper(I) Catalysts in ATRP
- Publication date
- Publisher
Abstract
The Cu<sup>I</sup> complex obtained in situ from Cu<sup>I</sup> and tris((4-methoxy-3,5-dimethylpyridin-2-yl)methyl)amine
(TPMA*)
is currently the most reducing and the most active catalyst for atom
transfer radical polymerizations (ATRP). The complex has a high affinity
for alkyl halides (ATRP pathway) but also has sufficient affinity
toward organic radicals to potentially participate in organometallic-mediated
radical polymerization (OMRP). Thus, the radical polymerization of <i>n</i>-butyl acrylate initiated by AIBN (azobisisobutyronitrile)
was significantly retarded, and the molecular weights decreased in
the presence of the Cu<sup>I</sup>/TPMA* complex. These results suggest
the presence of a Cu-mediated termination processes, even after the
amount of radicals generated from AIBN exceeded the initial amount
of Cu<sup>I</sup>/TPMA*. Nevertheless, in the presence of alkyl bromides,
which act as ATRP initiators for acrylates, control was gained through
metal-mediated halogen atom transfer, i.e., ATRP, not OMRP