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 CincinnatiCincinnati, OH 45221-0012

Jie Lian, L. M. Wang Dept. of Nuclear Engineering and Radiological

ScienceUniversity of MichiganAnn 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.

                    

                 

Carbon Nanotube FED Panel

Applications of Carbon Nanotubes

Carbon Nanotube computer

• 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

Plasma Process Parameters:

200 nm 200 nm

(A) (B)

HRTEM of coated MWNT

10 nm

Outer coating ~7 nm

inner coating 1~3 nm

(B)

5 nm

0.34 nm

Outer surface

(A)

HRTEM of coated MWNT

20 nm

Outer Coating ~5 nm

(A)

10 nm

Outer coating ~2 nm

(B)

HRTEM of coated MWNT

TOFSIMS of untreated Nanotubes

mass10 20 30 40

x104

0.0

0.5

1.0

1.5

2.0

2.5

inte

nsity

PNT.DAT TOF-SIMS IV

date : 09.17.2002time : 09:28

polarity : positive

Positive sample labeled NT

mass50 60 70 80

x104

0.0

0.5

1.0

1.5

inte

nsity

mass90 100 110 120

x102

0.0

1.0

2.0

3.0

4.0

5.0

inte

nsity

mass130 140 150 160

x102

0.0

0.2

0.4

0.6

0.8

1.0

inte

nsity

mass170 180 190 200

x101

0.0

1.0

2.0

3.0

4.0

5.0

inte

nsity

PNT.DAT 09/17/02 10:14:57 Compression Factor : 9

mass10 20 30 40

x105

0.0

0.2

0.4

0.6

0.8

1.0

inte

nsity

NNT.DAT TOF-SIMS IV

date : 09.17.2002time : 09:37

polarity : negative

sample labeled NT

mass50 60 70 80

x103

0.0

0.2

0.4

0.6

0.8

1.0

inte

nsity

mass90 100 110 120

x101

0.0

0.5

1.0

1.5

2.0

2.5

inte

nsity

mass130 140 150 160

x102

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

inte

nsity

mass170 180 190 200

x101

0.0

0.5

1.0

1.5

inte

nsity

NNT.DAT 09/17/02 10:13:43 Compression Factor : 9

positive negative

C1

C3C2

C4

C5

C6 C7H7+

C10H8+ C6H4-C2H3O2

+

C1

OH–

O–C2

C4–C4H

– Br–

Cl–

C7H8Cl–

C11H14Cl–C6H4-C4H5O2

+

TOFSIMS of C6F14- plasma-treated nanotubes

Mass0 10 20 30 40

x104

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Inte

nsity

PSMPL3.DAT TOF-SIMS IV

origin : date : 10.01.2002time : 14:05operator : Tonya

polarity : positivecycle time[us] : 100sputter time[s] : 6

Sample labeled 3

Mass40 50 60 70 80

x104

0.0

0.5

1.0

1.5

2.0

2.5

Inte

nsity

Mass80 90 100 110 120

x103

0.0

1.0

2.0

3.0

4.0

Inte

nsity

Mass120 130 140 150 160

x103

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Inte

nsity

Mass160 170 180 190 200

x102

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Inte

nsity

PSMPL3.DAT 10/01/02 14:10:08 Compression Factor : 9

negative

Mass10 20 30 40

x105

0.0

0.5

1.0

1.5

2.0

Inte

nsity

NSMPL3.DAT TOF-SIMS IV

origin : date : 10.01.2002time : 14:03operator : Tonya

polarity : negativecycle time[us] : 100sputter time[s] : 100

Sample labeled 3

Mass50 60 70 80

x104

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Inte

nsity

Mass90 100 110 120

x103

0.0

1.0

2.0

3.0

4.0

5.0

Inte

nsity

Mass130 140 150 160

x103

0.0

0.5

1.0

1.5

Inte

nsity

Mass170 180 190 200

x103

0.0

0.5

1.0

1.5

2.0

2.5

Inte

nsity

NSMPL3.DAT 10/01/02 14:09:07 Compression Factor : 9

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

10 nm

Coated SWNT

2.1 nm

HRTEM of coated SWNT

10 nm

Wall diameter ~1.4 nm

Polymer Coating

HRTEM of coated SWNT

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.