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

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.

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.

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

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

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

Synthesis Method of CNT III. Chemical Vapor Deposition (CVD) MWCNT 600-800 ° C2H2 → 2C + H2 SWCNT 900-1000 ° 2CO → C + CO2

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

Applications of Carbon Nanotubes Carbon Nanotube FED Panel Carbon Nanotube computer

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

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

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)

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

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+

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+

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

HRTEM of coated SWNT 10 nm Coated SWNT 2.1 nm

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

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.