Copper(I)-mediated living radical polymerization in the presence of oxyethylene groups: Online H-1 NMR spectroscopy to investigate solvent effects
UNSPECIFIED (2000) Copper(I)-mediated living radical polymerization in the presence of oxyethylene groups: Online H-1 NMR spectroscopy to investigate solvent effects. MACROMOLECULES, 33 (22). pp. 8246-8251. ISSN 0024-9297Full text not available from this repository.
The use of oxyethylene methacrylate monomers, initiators, and 1,2-diethoxyethane as a cosolvent in the living radical polymerization mediated by copper(I) pyridylmethanimine complexes has been studied. Online H-1 NMR monitoring of the reaction has been used to investigate the living radical polymerizations. Polymerization of poly(ethylene glycol) methyl ether methacrylate macromonomer (MeO(PEG)MA; M-n = 480) was carried out in toluene mediated by a copper(I) bromide/N-(n-propyl)-2-pyridylmethanimine catalyst, using phenyl alpha -bromoisobutyrate (1) as initiator. The measured number-average molar mass, M-n, of the product increases linearly with monomer conversion in close agreement to the theoretical M-n, with low polydispersity products (PDI < 1.2) achieved in all cases, as expected for a living polymerization. The overall rate of polymerization was very fast (ca. 90% conversion after 1 h at 90 <degrees>C) when compared to polymerization of benzyl methacrylate (BzMA) under similar conditions, indicating high values for k(p)[R*], where R* = active propagating species. The origin of this dramatic rate enhancement was investigated by carrying out the polymerization of MeO(PEG)MA over a range of temperatures and by the polymerization of alkyl methacrylates with a MeO(PEG)-derived macroinitiator. Polymerization of BzMA was carried out in I,2-diethoxyethane as solvent, which showed an enhanced rate when compared to polymerization in nonpolar/noncoordinating solvents. The high value of k(p)[R*] is ascribed to complexation of the oxyethylene groups at the copper in a dynamic state with the pyridylmethanime ligand complexation, which results in a more active catalyst.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||MACROMOLECULES|
|Publisher:||AMER CHEMICAL SOC|
|Date:||31 October 2000|
|Number of Pages:||6|
|Page Range:||pp. 8246-8251|
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