Catalytic Synthesis and Characterization of Biodegradable ...

Chapter 1
diamagnetic products, hydroxypiperidines structure (NOH), and oxo-piperidinium cations
(NO + ). Figure 1.6.1 shows such one-electron redox reactions of free nitric oxide derivatives.
Figure 1.6.1 The one-electron redox reactions of nitroxide free radicals. 178
Based on the redox properties of the nitroxyl radicals, polymers bearing stable radicals in
the side chains, also known as radical polymers, have been extensively studied as redox
resins which catalyze the oxidative and/or reductive reactions of organic compounds. For
example, poly(acrylate)-combined TEMPOs were synthesized and studied as a catalytic
reagent for the oxidation of alcohols into aldehydes and ketones. 179 The organic radical-based
or metal-free redox reagents have been recently reexamined from the perspective of green or
environmentally compatible chemical reaction processes.
In addition to this chemistry application, the robust electron exchange between unpaired
electrons in the polymer side chains suggests these radical polymers to be used for organic
electronic or magnetic materials. However, it is not until recently that the applications have
been intensively investigated for use in organic secondary battery or memory devices by our
group. The large population of the radical redox sites along the polymer chain allows the
effective redox gradient-deriven electron transport, which leads to organic batteries with large
energy density. On the other hand, polymers with nitroxyl radicals also attracts significant
interest to be as biomedical materials since the stable nitroxyl radials have been discovered to
have similar functions as nitric oxide (NO•) which was presence in many bioprocess such as
inflammation, blood clotting, blood pressure, neurotransmission, cardiovascular disorders and
antimicrobial property. 180-182 Thus, emphasis of this part of introduction would focus on the
radical polymers for organic electronic devices and biomedical applications.
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