Low-temperature living "radical" polymerization (atom transfer polymerization) of methyl methacrylate mediated by copper(I) N-alkyl-2-pyridylmethanimine complexes
UNSPECIFIED (1998) Low-temperature living "radical" polymerization (atom transfer polymerization) of methyl methacrylate mediated by copper(I) N-alkyl-2-pyridylmethanimine complexes. MACROMOLECULES, 31 (16). pp. 5201-5205. ISSN 0024-9297Full text not available from this repository.
This paper demonstrates that atom transfer polymerization of methyl methacrylate mediated by CuBr/N-alkyl-2-pyridylmethanimine complexes in toluene proceeds effectively at temperatures as low as 15 degrees C, while maintaining control over molecular weights and yielding narrow polydispersity indexes. The reaction can even be performed at - 15 degrees C with a number average molecular weight, M-n, of 6980 and a polydispersity, PDI, of 1.28 being achieved in 116 h; however, the molecular weight control is less effective. The polymerizations were performed at 90, 60, 40, and 15 degrees C with the first-order rate plots, molecular weight vs conversion plots, and final polydispersity indexes consistent with little or no termination-living/controlled polymerization. Methyl hydroquinone (MeHQ) has been demonstrated to accelerate the polymerization by a factor of 3-4 at temperatures below 40 degrees C; An activation energy, E-a, for polymerization in the absence of phenol was determined to be 60.3 kJ . mol(-1) and is significantly reduced to 44.9 kJ . mol(-1) in the presence of MeHQ. These results suggest that coordinating phenols modify the active polymerization center. The stereochemistry of the polymers produced are consistent with that observed for conventional free-radical polymerization in that the fraction of syndiotactic arrangements increases as the reaction temperature is lowered. At 90 degrees C, 59.1% rr triads are obtained with a persistence ratio of 0.924 and at -15 degrees C, 71.5% rr triads are obtained.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||MACROMOLECULES|
|Publisher:||AMER CHEMICAL SOC|
|Date:||11 August 1998|
|Number of Pages:||5|
|Page Range:||pp. 5201-5205|
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