Controlled radical polymerization of 1,3-butadiene. II. Initiation by hydrogen peroxide and reversible termination by TEMPO

Abstract

The radical polymerization of 1,3‐butadiene initiated by hydrogen peroxide and controlled by TEMPO is presented. Various parameters (e.g., the temperature and the [TEMPO]o/[H2O2]o initial molar ratio, γo), were studied to optimize the reaction. It was observed that the higher the temperature, the higher the yield, with optimal yields noted for γo = 0.10 with high molecular weights and broad polydispersity indexes. In addition, the kinetics of radical polymerization showed a decrease (by one order of magnitude) of the macroradical concentration all along the reaction. The ln [butadiene]/[butadiene]o increased relative to time and behaved linearly after 90 min. Further, the concentration of free TEMPO was ≈1000 times lower than the initial concentration, in good agreement with the decoloring of the medium. Thus a quasi‐living behavior of butadiene was noted from this system. Finally, the hydrolysis of these oligomers, either in the presence of zinc or thermally by means of a thin‐layer evaporator under vacuum allowed the production of telechelic hydroxy polybutadienes, the second technique enabling the obtaining of higher molecular weights by coupling and the recovery of TEMPO. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3293–3302, 2000

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