A spiral diffusion path for non-spherical organic molecules in carbon nanotubes was studied. The classical molecular dynamics simulations and density functional theory calculations were used to investigate the diffusive behavior of ethane and ethylene in single-walled carbon nanotubes (table 6). It was concluded that the simulation and calculations have quantified the level of alignment of C-C bond in small, non-spherical hydrocarbon molecules with C-C bonds in CNT walls that maximized molecular-CNT interactions.

Predictions of a Spiral Diffusion Path for Nonspherical Organic Molecules in Carbon Nanotubes. Mao, Z., Sinnott, S.B.: Physical Review Letters, 2002, 89[27], 278301-4

 

Table 6

Diffusion coefficient of molecules diffusing through C nanotubes

 

Type

Diameter (Å)

Diffusant

D (cm2/s)

(17,0)

13.5

C2H6

1.04 x 10-4

(17,0)

13.5

C2H4

9.28 x 10-5

(21,0)

16.7

C2H6

4.82 x 10-5

(21,0)

16.7

C2H4

3.75 x 10-5

(24,0)

19.1

C2H6

1.94 x 10-5

(24,0)

19.1

C2H4

1.36 x 10-5

(28,0)

22.2

C2H6

7.95 x 10-6

(28,0)

22.2

C2H4

6.89 x 10-6

(10,10)

13.75

C2H6

9.88 x 10-5

(10,10)

13.75

C2H4

9.20 x 10-5

(12,12)

16.5

C2H6

5.02 x 10-5

(12,12)

16.5

C2H4

4.14 x 10-5

(14,14)

19.25

C2H6

1.78 x 10-5

(14,14)

19.25

C2H4

1.25 x 10-5

(16,16)

22.1

C2H6

8.24 x 10-6

(16,16)

22.1

C2H4

6.98 x 10-5