Investigation of Nitroxide Radical Coupling Reaction in Wide Temperature Range and Different Catalyst System

The effect of temperature, catalyst system, and the structure of bromine connected groups on the nitroxide radical coupling (NRC) reaction is investigated in details. A series of polymers with different bromine connected groups as poly (tert-butyl acrylate) (PtBA-Br), polystyrene (PS-Br), and poly (methyl methacrylate) (PMMA-Br) are prepared by atom transfer radical polymerization first, then the bromine-containing polymers were coupled with 2,2,6,6-tetramethylpiperidinyl-1-oxy-containing poly(c-caprolactone) (PCL-TEMPO) in different catalyst systems as CuBr/PMDETA, Cu degrees/PMDETA and CuBr/Cu degrees/PMDETA in the temperature range from 90 C to 25 C. The result shows that the catalyst system of CuBr/Cu degrees/PMDETA is the best one for NRC reaction, in which the NRC reaction could be conducted in high efficiency in the wide temperature range from room temperature to high temperature. The efficiency of NRC reaction between PtBA-Br and PCL-TEMPO is more than 85% in the temperature range from 25 to 75 degrees C, the efficiency between PS-Br and PCL-TEMPO is more than 90% from 25 to 90 degrees C, and the efficiency between PMMA-Br and PCL-TEMPO is more than 90% only at the room temperature. The effect of bromine connected groups on the NRC reaction is discussed. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2991-2999, 2010