Assembly of β-Cyclodextrins Acting as Molecular Bricks onto Multiwall Carbon Nanotubes

Multiwall carbon nanotube (MWCNT)−β-cyclodextrin (β-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 β-CD debundled MWCNT bundles and endowed MWCNTs with uniform architecture. Furthermore, the obtained MWCNT−β-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 β-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−β-CD composites originated from (1) van der Waals forces between MWCNTs and β-CD and (2) hydrogen-bonding interaction between adjacent β-CD molecules. Both forces induced the ordered assembly and arrangement of β-CD onto the surface of MWCNTs, where β-CD molecules acted as molecular bricks.