| 16375366 |
Jarroux N, Guegan P, Cheradame H, Auvray L: High conversion synthesis of pyrene end functionalized polyrotaxane based on poly (ethylene oxide) and alpha-cyclodextrins. J Phys Chem B. 2005 Dec 22;109(50):23816-22.
We describe the quantitative synthesis of new pyrene labeled cyclodextrin-based polyrotaxane starting from pseudopolyrotaxane of alpha,omega-dimethacrylate poly (ethylene oxide) (PEO) and alpha-cyclodextrins (alpha-CDs). Using a solvent mixture (H2O/dimethyl sulfoxide (DMSO)), an almost quantitative conversion in polyrotaxane can be achieved using the coupling reaction between methacrylic functions and 1-pyrene butyric acid N-hydroxysuccinimide ester. This result is due to the fast blocking reaction of the pseudopolyrotaxane telechelic functions. The polyrotaxanes are characterized by NMR, size exclusion chromatography (SEC), and small-angle neutron scattering (SANS). A rodlike structure of the polyrotaxane is evidenced by SANS, and a persistence length of 70 A is determined. This result corresponds to an almost completely stretched PEO chain of 1000 g.mol (-1) molecular weight. We furthermore studied the opposite case of low packing density polyrotaxanes that were also silylated to suppress interactions between cyclodextrins. We observed a random coil structure only for silylated low packed polyrotaxane. This result demonstrates that both hydrogen bonding and packing density can explain the rodlike structure of cyclodextrin-based polyrotaxane. |
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