3106 Chan et al.
Macromolecules, Vol. 38, No. 8, 2005
Table 3. Summary of the Thermal Characteristics of the CDs, the Synthesized Star PCL, and Their Inclusion Complexes
Td,freea (°C)
γ-CD
Td,complexesb (°C)
Td,complexesb (°C)
entry
R-CD
star-PCL
R-CD
star-PCL
γ-CD
star-PCL
S1
S2
S3
313
313
313
314
314
314
360
362
365
325
324
327
382
384
384
312
311
315
380
381
383
a The values of Td for the free CDs and each component of the star PCL were determined from TGA curves as the point at which 5%
mass loss occurred at each degradation step. b The values of Td for each component in the star-polymer/CDs were determined from TGA
curves as the point at which 5% mass loss occurred at each degradation step.
thermal stability of the star PCLs. The thermal stabili-
ties of the CDs in their ICs are also higher than those
of the pure CDs, which implies that the presence of
guests included within the CD channels can improves
the thermal stability of the original CDs.
Acknowledgment. The authors like thank the
National Science Council, Taiwan, Republic of China,
for financially supporting this research.
References and Notes
According to the stoichiometries ratios (ꢀ-CL unit:CD)
that we determined by 1H NMR spectroscopy, we believe
that the R-CD/star PCL ICs contain single PCL chains
in each R-CD channel while the γ-CD/star PCL ICs
contain two PCL chains; i.e., they possess similar
architectures to those found in the frameworks of the
corresponding CD/linear PCL ICs. Scheme 4 illustrates
some possible structures for the inclusion complexes
formed between the star PCLs and R-CD/γ-CD, with
eight- and four-rod arms attached to the POSS core,
respectively. Another possible structure for the γ-CD/
star PCL ICs might form as a result of γ-CD containing
two PCL chains simultaneously within the one channel.
The inclusion of arms from two different star PCLs
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of the unequal splaying of each arm of the star polymer.
As a result, a gellike lightly physically cross-linked
structure would form. Scheme 5 presents a proposed
structure for this cross-linked γ-CD/star PCL IC where
the POSS core would be the only uncomplexed material
located between the CD IC crystalline cross-links.
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