| Preparation and Characterization of Conjugated Polypseudorotaxane Poly (Pyrrole/α-Cyclodextrin) |
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Writer: Yujie Chen, Wei Wu, Weiguang Pu, Sanxiong He Publication: International Journal of Polymer Analysis and Characterization, 2010,15(1)：43-53 Abstract: Conjugated polypseudorotaxanes polypyrrole/α-cyclodextrin and polypyrrole/β-cyclodextrin (PPy/α-CD and PPy/β-CD) were synthesized by chemical oxidative polymerization of pyrrole in the presence of α-CD and β-CD respectively, using hydrophobic binding to promote threading of the cyclodextrin units. The FT-IR spectra and wide-angle X-ray diffraction patterns verified that pyrrole-CD (Py-CD) rotaxanes were presented in the polypyrrole (PPy) chains. From SEM characterization, neat PPy and PPy/β-CD exhibit agglomerated and spherical morphology, while PPy/α-CD possesses typical dentritic structure with favorable orientation. The diameter of PPy/α-CD conjugated polypseudorotaxane wire equaled about 200 nm. Based on elemental analysis, the molar ratio of α-CD to pyrrole was 1:5 and β-CD to pyrrole was 1:24. Owing to the irregular Py-CD rotaxanes, the conductivity of PPy/CDs was decreased by one order of magnitude compared to PPy. The PPy/CDs exhibited reduced redox reversibility, as confirmed by an obvious shift of oxidation peak and a lower current in the voltammograms. The starting decomposition temperature of PPy/α-CD was increased by 60°C, indicating the superior thermal stability of polypseudorotaxanes through thermogravimetric analysis (TGA). The mechanism for threading and unthreading between of CDs and PPy chains in the polymerization was also proposed in this work. To conclude, remarkable characteristics of polypseudorotaxane PPy/CDs were studied in this paper, which could promise its potential in application as molecular wire.
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