Dextran complexes with single-walled carbon nanotubes

Formation of surface and inclusion complexes of single-walled carbon nanotubes (SWCNT) with dextrans of M-w 6000 to 2 000 000 was proven spectrally, rheologically, and calorimetrically. Band shifts in the Raman spectra, increase in the viscosity of aqueous solutions of particular dextrans after admixture of SWCNT, and enthalpies of melting of those complexes were independent on molecular weight of dextrans. Computational simulations were performed using the HyperChem 7 and Gaussian 03 packages, starting from a model of single, short SWCNT and linear dextran chain made of 12, 18 or 24 beta-D-glucose units. The simulation indicated that dextran chains composed of 12 or 18 beta-D-glucose units only partly enveloped SWCNT and the intermolecular interactions in both terminals of the chains prevailed. The dextran containing 24 beta-D-glucose units fully enveloped SWCNT. However, the role of SWCNT in the envelop formation was limited solely to its hydrophobic interactions with the central part of the dextran chain.