Molecular dynamics study of radial pressure transmission in multiwalled carbon nanotubes

The pressure response of multiwalled carbon nanotubes (MWCNTs) to the radial hydrostatic pressure is studied by using constant pressure molecular dynamics simulations for finite systems. The inner tube is effectively protected by the outer tube against the external pressure. The pressure transmission efficiency of MWCNTs depends upon both the size and morphology combination of the tubes. The larger the tube is, the higher the pressure transmission efficiency will be. The pressure transmission in commensurate MWCNTs is more efficient than that in incommensurate ones. Based on the present simulations, an experimental method is suggested for measuring the pressure transmission efficiency of MWCNTs.

Figure 1

Response pressure as a function of the external pressure for (5,5)@(10,10) DWCNT (left) and (5,5)@(10,10)@(15,15) TWCNT (right). The system response pressure is exactly the same as the external pressure. The response pressure of the inner tube is much smaller than that of the outer one before structural transition occurs.

Figure 2

Pressure transmission efficiency of commensurate armchair/armchair $(n,n)@(n+5,n+5)$ DWCNTs (with $n=5,6,7,8,9,10$) vs the outer tube radius (solid cycles). The commensurate zigzag/zigzag (10,0)@(19,0), (17,0)@(26,0) (open triangles), and incommensurate (6,6)@(19,0), (10,10)@(26,0) (open squares) DWCNTs are also shown for comparison. The transmission efficiency increases with the tube radius. The transmission efficiency of incommensurate DWCNTs is smaller than that of commensurate ones with the same size.

Figure 3

Energy of the highest $E_{2g}$ mode vs external pressure (left) and response pressure (right) for (5,5) SWCNT and the same tube as inner one in a (5,5)@(10,10) DWCNT.