Horizontally aligned surface segments enhancing the adhesion of carbon nanotube forests

The excellent mechanical properties of carbon nanotube (CNT) and low effective modulus of its forest makes CNT forest (CNTF) promising in dry adhesives. However, the low contact efficiency of buckled nanotube segments on the surface of the CNTF weakened its adhesion strength, which is far below the theoretical value. To improve the orientation, density, and arrangement of these nanotube segments, a layer of patterned aluminum was added to the conventional catalyst. Thus, a CNTF with densely-packed, horizontally-aligned surface nanotube segments was obtained. Nanoindentation results showed that the adhesion force of this CNTF could reach up to 13.69 mN under optimized conditions, nearly 5.5 times the best results of similar works. The results of coarse-grained (CG) simulations revealed the lateral stretching of these nanotube segments induced bond energy variation made a major contribution to the superior adhesion performance. The formation mechanism of these surface nanotube segments was also thoroughly analyzed.