Assembly of β-cyclodextrins acting as molecular bricks onto multiwall carbon nanotubes

Multimall carbon nanotube (MWCNT)-beta-cyclodextrin (beta-CD) composites have been successfully synthesized through combining polymer wrapping and layer-by-layer self-assembly techniques. The obtained materials were characterized in detail by X-ray diffraction, thermogravimetric analysis-differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and nulcear magnetic resonance. The analytical results indicated that the introduction of beta-CD debundled MWCNT bundles and endowed MWCNTs with uniform architecture. Furthermore, the obtained MWCNT-beta-CD composites possessed good dispersibility in both ethanol and water media, and the solution was found to be very stable for several weeks. To further clarify the interaction between MWCNTs and beta-CD, a molecular mechanics (MM) method was performed for the first time. Combining experimental results with MM simulations, a reasonable formation mechanism is also presented in this paper. The driving forces for the formation of well-defined MWCNT-beta-CD composites originated from (1) van der Waals forces between MWCNTs and beta-CD and (2) hydrogen-bonding interaction between adjacent beta-CD molecules. Both forces induced the ordered assembly and arrangement of beta-CD onto the surface of MWCNTs, where beta-CD molecules acted as molecular bricks.