Publications (2)0 Total impact
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ABSTRACT: The interaction between the polysaccharide alginate and cucurbituril (CB) in aqueous solution has been investigated by static fluorescence spectroscopy, dynamic light scattering, transmission electron microscopy, circular dichroism (CD) and zeta potential. Results showed that the interactions between the alginate and the CB lead to the formation of micelle-like nanometer-sized aggregates due to electrostatic interaction and iondipole interaction. The size of aggregates depends on the concentration of alginate. In our experiment, only when the concentration of sodium alginate was 0.05 wt%, were uniform micelle-like aggregates achieved. With the increase in the concentration of alginate, the size of aggregates increased. When the concentration of alginate was above 0.2 wt%, the aggregates became precipitates after 48 h of storage at room temperature. As the concentration of sodium alginate was raised to about 0.5 wt%, gelation appeared. At low concentrations of alginate (around 0.01 wt%), few micelles-like nanometer-sized aggregates were observed. The aggregation also depends on the mole ratio of CB/carboxyl in alginate. Isolated micelle-like aggregates prevailed at low stoichiometric mole ratio of CB/carboxyl in alginate and the clusters were predominant with increasing the mole ratio of CB/carboxyl in alginate due to the decrease of charges at the surface of the micelle-like aggregates.Carbohydrate Polymers.
Article: Side-chain pseudopolyrotaxanes by threading cucurbituril onto quaternized poly-4-vinylpyridine derivative: Synthesis and properties[show abstract] [hide abstract]
ABSTRACT: A novel side-chain pseudopolyrotaxanes 4 is synthesized from cucurbituril (CB) and quaternized poly-4-vinylpyridine derivative 3 in water by simple stirring at room temperature. CB beads are localized on hexamethylene units in side chains of 3 as found by NMR studies, and the hydrophobic and charge-dipole interactions are the driving force. The degree of threading (q/n, the average number of CB beads per repeat recognition unit of 3) can be controlled from 0.2 to 1.0 by controlling the amount of CB added. The reduced viscosity of pseudopolyrotaxanes in aqueous solution has smaller change with the change of the concentration or temperature, which is consistent with the hydrodynamic radius and more rigid chain conformation because of the threaded CB. DLS results show the average hydrodynamic diameter (Dh) of the pseudopolyrotaxanes in solution increases with the increasing of CB threaded. The pseudopolyrotaxanes have higher thermal stability and intensity of absorption band than the parent polymer 3 as found by TGA and UV–vis studies. The decomposition temperature and intensity of absorption increase with increasing amount of CB threaded. The effect of NaI to pseudopolyrotaxanes is studied by the transmittance with UV–vis, and the result shows that NaI is the satisfied precipitant to the pseudopolyrotaxanes.Polymer. 47(15):5267-5274.