Covalent chemistry of single walled nanotubes

1. Covalent chemistry of single walled nanotubes Krishna Prasad Bastola, Graduate Student, Chemistry Department Oklahoma State University

2. SWNTs: • High metallic conductivity. • High tensile strength, high elasticity. • High chemical and thermal stability. • Ability to absorb gas molecules as nano capillaries.

3. Other applications of SWNTs need chemical modification • Two types of chemical modification : • non covalent interaction • Covalent Interaction (functionalization of SWNTs)

4. Solubility of SWNT as such in different solvents is about 5mg/50 ml. Solubility increases to 1mg/ml after functionalization. Attachment of desired moieties in SWNTs possible only in solution. AFM of functionalized tube AFM of unfunctionalized tube Source:Texas institutes for intelligent bio nanomaterials, NASA

5. Steps involved in functionalization Introduction of COOH groups Changing COOH to COCl Amidation of COCl by amine such as octadecylamine(ODA) Source: J. Mater. Chem.2002,1952

6. Schematics of functionalization route.

7. Characterization of functionalized SWNTs • No standard techniques yet. • ATR good tools to identify functional groups (FG) • NMR has some application but to interpret spectra is difficult • Raman spectroscopy is useful specially for the (FG) in side wall of SWNT • TGA ( thermal gravimetric analysis) used extensively as the FG are labile. • SEM,AFM, TEM, and STM microscopy's are also very useful.

8. Potential applications of functional SWNTs. Fluorinated SWNTs as cathode in lithium electrochemical cell. Polyethyleneimine-SWNT in neuronal growth Functionalized SWNT as CFM tips

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10. Thank You very much