Deposition of Extremely Thin Polymer Films on Carbon Nanotube Surfaces by a Plasma Treatment

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 45221-0012 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 600-800 ° C2H2→ 2C + H2 SWCNT 900-1000 ° 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: 13.56 MHz • Input power: 5-30 Watt • Treatment time: 5-30 minutes • Per batch: 0.2-1 grams

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

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

13. (A) (B) Outer Coating ~5 nm Outer coating ~2 nm 20 nm 10 nm HRTEM of coated MWNT

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

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

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

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

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

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.