1. Deposition of Extremely Thin Polymer Films on Carbon Nanotube Surfaces by a Plasma Treatment
Peng He, Donglu Shi, Wim J. van Ooij
Dept. of Materials Science and Engineering
University of Cincinnati
Cincinnati, OH
Jie Lian, L. M. Wang
Dept. of Nuclear Engineering and Radiological Science
University of Michigan
Ann Arbor, MI 48109

2. What are Carbon Nanotubes?
Carbon nanotube is a new carbon allotrope that was first discovered in 1991 by Dr. Sumio Iijima at NEC. It has a nanometer-scale hollow tubular structure and a different atomic arrangement from graphite, diamond and C60 bucky-ball C the other three known carbon structures. Its unique and promising properties have attracted the attention of researcher around the world and led to active R&D efforts in the commercial industries.

3. Properties of Carbon nanotubes
the highest elastic module, and mechanical strength that is approximately 200 times stronger than steel.
novel electronic properties.
high thermal conductivity.
excellent chemical and thermal stability.
promising electron field emission properties.
high chemical (such as lithium) storage capacity.

4. SWNT and MWNT Single-Wall Nanotube (SWNT) Multi-Wall Nanotube (MWNT)
TEM Image of MWCNT

5. Synthesis Method of CNT
I. Arc Discharge Method
Without Catalyst
→ MWNT
With Catalyst
(Co, Ni, Fe, etc.)
→ SWNT

6. Synthesis Method of CNT
II. Laser Ablation Method
Without Catalyst
→ Fullerene
With Catalyst
(Co, Ni, Fe, etc.)
→ SWNT

7. Synthesis Method of CNT
III. Chemical Vapor Deposition (CVD)
MWCNT °
C2H2 → 2C + H2
SWCNT °
2CO → C + CO2

8. Applications of Carbon Nanotubes
                                     
telecommunication, cell phones.
rechargeable lithium batteries.
medical image equipment.
computer display.
multi-functional composites for aircraft.

9. Applications of Carbon Nanotubes
Carbon Nanotube FED Panel
Carbon Nanotube computer

10. Plasma Process Parameters:
Basic pressure: < 40 mTorr
Monomer used: C6F14
Monomer pressure: 200 ~ 250 mTorr
System total pressure: < 300 mTorr
RF frequency: MHz
Input power: 5-30 Watt
Treatment time: 5-30 minutes
Per batch: grams

11. HRTEM of coated MWNT
200 nm
(A)
(B)

12. HRTEM of coated MWNT (B) 5 nm (A) 10 nm inner coating 1~3 nm
Outer coating ~7 nm
inner coating 1~3 nm
(B)
5 nm
0.34 nm
Outer surface
(A)

13. HRTEM of coated MWNT (A) (B) 20 nm 10 nm Outer Coating ~5 nm

14. TOFSIMS of untreated Nanotubes
positive
negative C1 C3 C2 C4 C5 C6
C7H7+
C10H8+
C6H4-C2H3O2+
OH– O–
C4–
C4H–
Br–
Cl–
C7H8Cl–
C11H14Cl–
C6H4-C4H5O2+

15. TOFSIMS of C6F14- plasma-treated
nanotubes
negative F–
CF3–
C3F3–
C3F5–
C3F7–
C5F7–
C4F7–
C2F5–
C5F3–
C7F3–
C4F5–
C5F5–
F2–
C2F–
positive C+ H+
CF+
CF3+
C3F3+
C2F4+
C2F5+
C3F5+
C3F7+
C4F7+
C5F7+
C4F6+
C2F+
C2H3+
C2H5+

16. HRTEM of coated SWNT 10 nm Coated SWNT bundles SWNT bundles
Polymer Coating

17. HRTEM of coated SWNT
10 nm
Coated SWNT
2.1 nm

18. HRTEM of coated SWNT
10 nm
Wall diameter ~1.4 nm
Polymer Coating

19. Conclusion
An ultrathin film of polymer deposited on the surfaces of MWNT by means of a plasma polymerization treatment.
The polymer layer is not only uniform on outer surfaces, but also deposited in an extremely thin thickness of 2~7 nm.
This unique plasma coating opens great possibilities for future novel engineering applications.