Tacticity Influence on the Electrochemical Reactivity of Group Transfer Polymerization-Synthesized PTMA

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• 作者：Hugo A. L贸pez-Pe帽a ; Lindsay S. Hern谩ndez-Mu帽oz ; Bernardo A. Frontana-Uribe ; Felipe J. Gonz谩lez ; Ignacio Gonz谩lez ; Carlos Frontana ; Judith Cardoso
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：May 10, 2012
• 年：2012
• 卷：116
• 期：18
• 页码：5542-5550
• 全文大小：417K
• 年卷期：v.116,no.18(May 10, 2012)
• ISSN：1520-5207

文摘

Spectroscopic, thermal, and electrochemical characterization results are presented for the redox active polymer poly(2,2,6,6-tetramethyl-1-piperinidyloxy-4-yl methacrylate) or PTMA, synthesized by group transfer polymerization (GTP), and its precursors 4-hydroxy-tetramethylpiperidine-N-oxyl (HO-TEMPO) and 4-methacryloyloxy-tetramethylpiperidine-N-oxyl (MO-TEMPO). DSC analysis of synthesized PTMA showed that the glass transition temperature (T_g) of the polymer structure occurs at 155 掳C, corroborated by dynamic mechanical analysis (DMA), which is higher when compared with T_g data for PTMA synthesized by other methods. Also, the amount of radical species present in PTMA synthesized by GTP reactions (100%) is higher than the values typically upon synthesizing PTMA by radical polymerization. Electrochemical and spectroelectrochemical-electron spin resonance studies in acetonitrile revealed two redox events in the PTMA polymer, one of which is reversible, accounting for ca. 80% of the spins in the polymer and giving rise to the battery behavior. The other redox event is irreversible, accounting for the remaining ca. 20% of spins, which has not previously been reported. These two redox events are linked to a structural property associated with the tacticity of the polymer, where the reversible feature (responsible for cathode behavior) is the dominant species. This corresponds to a number of isotactic domains of the polymer (determined by high temperature ¹H NMR). The second feature accounts for the three-line impurity observed in the ESR, which has been reported previously but poorly explained, associated to the number of heterotactic/syndiotactic triads.