Catalytic Synthesis and Characterization of Biodegradable ...

Chapter 5
Figure 1. 1 H NMR spectra of HO-PLA-OH (A) and CPAD-PLA-CPAD (B).
Figure 2 showed the 1 H NMR spectra of PTAm-b-PLA-b-PTAm triblock copolymers. All
the resonances attributed to PLA and PTAm repeat units were detected, which clearly
indicated the successful preparation of the triblock copolymers. The degree of polymerization
of PTAm block can be calculated based on the integration of proton peak c at 4.19 ppm from
piperidine and the proton peak a at 5.18 ppm of the methine in PLA. Triblock copolymers
with different PTAm block length can be obtained by varying the monomer feed. The
molecular weights of the copolymers are summarized in Table 1. The yields were higher than
80%, indicating the reaction is more effective than that described in Chapter 4. The
copolymers had low polydispersities, and the GPC profiles of the copolymers were all single
and symmetrical peak. These implied that all the macromonomers have initiated the TAP
monomers successfully and no homopolymerization occurred.
Figure 2. 1 H NMR spectrum of PTAP-b-PLA-b-PTAP.
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