STRUCTURAL MODIFICATION OF NANOPOROUS CARBON WITH SINGLE WALL CARBON NANOTUBE
Open Access
- Author:
- Yi, Bo
- Graduate Program:
- Chemical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 04, 2007
- Committee Members:
- Henry C Foley, Committee Chair/Co-Chair
Seong H Kim, Committee Member
Darrell Velegol, Committee Member
Elizabeth C Dickey, Committee Member - Keywords:
- poly(furfuryl alcohol)
nanoporous carbon
single wall carbon nanotube
carbon
nanocomposite - Abstract:
- A novel CC nanocomposite was synthesized by pyrolysis of well dispersed individual functionalized SWNTs in a thermosetting resin, poly(furfuryl alcohol) (PFA). Strong interaction between SWNT and nanoporous carbon derived from PFA (PFA-NPC) was obtained with this strategy and the integrity of SWNTs was maintained after heat treatment. Usually, it is challenging to separate SWNT bundles and disperse them in preparation of composites. 50 wt% SWNT/NPC composites prepared with solution blending showed mass transfer rate of ~140% higher than the original NPC. The improvement was not significant due to poor dispersion and the bundle structure of SWNTs. Functionalization of SWNTs successfully separated the SWNT bundles and solved the problems of dispersion. In this process, the SWNTs were first functionalized with sulfonic acid groups (SA-SWNT) on sidewall. Then they were converted to PFA-grafted SWNT (PFA-SWNT) by in situ polymerization of furfuryl alcohol (FA). NPC/SWNT nanocomposite was generated by pyrolysis of PFA-SWNT at 600˚C. The structural transformation of NPC/SWNT at high temperature was studied by heating it at temperatures from 1200 to 2000 ˚C in vacuum and characterized with HRTEM and Raman spectra. It was found that NPC and SWNT coalesce upon heat treatment and NPC tended to graphitize along the axis of neighboring nanotubes at temperature higher than 1400 ˚C. Complete graphitization of NPC and SWNTs was obtained at 2000 ˚C, when the NPC transformed to graphitic nanoribbons (GNRs) and SWNT or DWNT collapsed within the confines of the GNR. The mass transfer rate in 0.05 wt% SWNT/NPC nanocomposite was ~2 times higher than that in the pure NPC. Similar improvement required SWNT concentration of ~60 wt% in the SWNT/NPC composites prepared by solution blending. SWNT/NPC nanocomposite fibers prepared from 0.1 wt% SA-SWNT/FA had ~13% increase of Young’s modulus over the pure NPC fibers when they were pyrolyzed at 400 – 1600 ºC. The augment was slightly higher than Halpin-Tsai’s model prediction for composites with randomly dispersed fibers, indicating that the strong interaction between NPC and SWNT strengthened the material.