Reversible tailoring of mechanical properties of carbon nanotube forests by immersing in solvents

• Published in: Carbon (New York) Vol. 69; pp. 178 - 187
• Main Authors: Pour Shahid Saeed Abadi, Parisa, Maschmann, Matthew R., Mortuza, S.M., Banerjee, Soumik, Baur, Jeffery W., Graham, Samuel, Cola, Baratunde A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2014; Elsevier
• Subjects: Buckling; Carbon nanotubes; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Forests; Fullerenes and related materials; diamonds, graphite; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical instruments, equipment and techniques; Mechanical properties; Micromechanical devices and systems; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics; Soaking; Solvents; Specific materials; Stiffness; Toluene; Carbon nanotubes; Mechanical properties; Forests; Microelectromechanical device
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2013.12.004

The mechanical behavior of carbon nanotube (CNT) forests soaked in three solvents – toluene, acetonitrile, and isopropanol – is examined. Effective stiffness of the structure is evaluated in the dry and wet condition by micro-indentation using a 100μm flat punch. With soaking of CNT forests in solvents, the stiffness decreases and deformation mechanism changes from buckling concentrated close to the bottom of the CNT forest to a distribution of local buckles along the height and global buckling of the entire length of CNTs. We use molecular dynamics simulations to relate the experimental observations to the reduced mechanical support from neighbor CNTs due to a decreased magnitude of van der Waals (vdW) interactions in the presence of solvents. Toluene, which produces the lowest average measured stiffness between the three solvents, produces the lowest vdW forces between individual CNTs. Furthermore, wet–dry cycling of CNT forests shows the reversibility and repeatability of change of stiffness by immersing in solvents. The results show that soaking CNT forests in solvents could be useful for applications such as interface materials where lower stiffness of CNT forests are needed and applications such as energy absorbing materials in which re-setting of stiffness is required.