Effect of [Pyridylmethanimine]/[CuI] Ratio, Ligand, Solvent and Temperature on the Activation Rate Constants in Atom Transfer Radical Polymerization

✍ Scribed by Wei Tang; Ajaya Kumar Nanda; Krzysztof Matyjaszewski

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 133 KB
• Volume: 206
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200500058

✦ Synopsis

Abstract

Summary: The effect of [L]/[Cu^I^] ratio, ligand, the choice of solvent and temperature on the activation rate constants in ATRP with catalyst complexes formed with two pyridylmethanimine ligands [PMI, i.e., N‐propyl‐pyridylmethanimine (NPPMI) and N‐octyl‐pyridylmethanimine (NOPMI)] were studied. Maximal values for the apparent rate constants were observed at an [L]/[Cu^I^] ratio of ∼2/1 and 1/1 in polar and nonpolar solvents, respectively. This is similar to the results obtained with the Cu^I^/bpy system and was attributed to the formation of [Cu^I^/L~2~]^+^Br^−^ and [Cu^I^/L~2~]^+^Cu^I^Br species. The Cu^I^/NPPMI system was only soluble in polar reaction media; however, the Cu^I^/NOPMI complex was soluble in both polar and less polar reaction media. The activation rate constants increased with increasing temperature and the value of activation energy (E~a~) for Cu^I^/NPPMI in the activation process was 58.1 kJ · M^−1^ · K^−1^.

Arrhenius plot of ln k~a~ versus 1/T for the activation process for NPPMI and bpy in acetonitrile; [Cu^I^Br/NPPMI~2~]~0~ ([Cu^I^Br/bpy~2~]~0~)/[EtBriB]~0~/[TEMPO]~0~/[TCB]~0~ = 20/1/10/2 × 10^−3^ M.

magnified imageArrhenius plot of ln k~a~ versus 1/T for the activation process for NPPMI and bpy in acetonitrile; [Cu^I^Br/NPPMI~2~]~0~ ([Cu^I^Br/bpy~2~]~0~)/[EtBriB]~0~/[TEMPO]~0~/[TCB]~0~ = 20/1/10/2 × 10^−3^ M.