Catalytic Synthesis and Characterization of Biodegradable ...

Chapter 4
attributed to the amide group. The GPC elution curve for PTAm-g-PLA gave a unimodal peak,
which indicated that there was no undesired homopolymer residue in the final product. Based
on these results, it was concluded that the PTAm-g-PLA copolymers were successfully
prepared by this method.
Figure 4.3 FTIR spectra of PTAP-g-PLA2 (A) and PTAm-g-PLA2 (B).
4.3 Electrochemical Properties
Based on the presence of the nitroxide radicals, the copolymers exhibited
electrochemically reversible properties similar to that of TEMPO. The cyclic voltammogram
(CV) of the copolymer at different scan rates were shown in Figure 4.4. The CV curves for
the copolymer were recorded in the potential range of 0.00 to 1.30 V. The response revealed a
highly reversible redox property at around 0.63 V vs. Ag/AgCl, which was assigned to the
oxidation of the nitroxide to the corresponding oxoammonium cation. The redox potential
(0.63 V vs. Ag/AgCl) was in good agreement with that of the PTAm homopolymer (0.68 V vs.
Ag/AgCl). Moreover, the peak current is proportional to the sweep rate, suggesting a fast
electron transfer process in the copolymer film.
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