‘Living’ radical polymerization of styrene mediated by spiro ring-substituted piperidinyl-N-oxyl radicals. The effect of the spiro rings on the control of polymerization |
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Authors: | Yozo Miura Ayako IchikawaIsao Taniguchi |
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Affiliation: | Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan |
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Abstract: | The bulk radical polymerizations of styrene (St) at 80-120 °C in the presence of 6-aza-7,7-dimethyl-9-hydroxyspiro4.5]decane-6-yloxyl (1) and 1-aza-2,2-dimethyl-4-hydroxy5.5]undecane-1-yloxyl (2) were studied. At 100 and 120 °C, the polymerizations were well controlled by those nitroxides to give poly(St)s with narrow polydispersities. On the other hand, the polymerization mediated by 2 at 80 °C showed a good ‘livingness’ of polymerization, but 1 had a poor ability to control the polymerization to give poly(St) with a broad polydispersity of 1.52. The rate constants (kact) for the homolysis of the NO-C bond of the alkoxyamines prepared from 1 and 2 were measured at 333-373 K, and the Aacts and Eacts values were determined to be 2.8×1013 s−1 and 128 kJ mol−1 (1) and 4.0×1013 s−1 and 125 kJ mol−1 (2), respectively, from the Arrhenius plots. These results are compared with those for the structurally related piperidinyl-N-yloxyl radicals including TEMPO. |
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Keywords: | Living radical polymerization Nitroxide Styrene |
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