The physics of adhesion and stiction of one-dimensional nanostructures such as nanotubes, nanowires, and biopolymers on different material substrates is of great interest for the study of biological adhesion and the development of nanoelectronics and nanocomposites. Here, we combine theoretical models and a new mode in the atomic force microscope to investigate quantitatively the physics of nanomechanical peeling of carbon nanotubes and nanocoils on different substrates. We demonstrate that when an initially straight nanotube is peeled from a surface, small perturbations can trigger sudden transitions between different geometric configurations of the nanotube with vastly different interfacial energies. This opens up the possibility of quantitative comparison and control of adhesion between nanotubes or nanowires on different substrates.

Dynamic atomic force microscopy (dynamic AFM) with carbon nanotube tips has been suggested as an enabling tool for high precision nanometrology of critical dimension features of semiconductor surfaces. We investigate the performance of oscillating AFM microcantilevers with multi-walled carbon nanotube (multi-walled CNT) tips interacting with high aspect ratio structures while in the attractive regime of dynamic AFM. We present experimental results on SiO 2 gratings and tungsten nanorods, which show two distinct imaging artefacts, namely the formation of divots and large ringing artefacts that are inherent to CNT AFM probe operation. Through meticulous adjustment of operating parameters, the connection of these artefacts to CNT bending, adhesion, and stiction is described qualitatively and explained.

The interplay between local mechanical strain energy and lateral frictional forces determines the shape of carbon nanotubes on substrates. In turn, because of its nanometer-size diameter, the shape of a carbon nanotube strongly influences its local electronic, chemical, and mechanical properties. Few, if any, methods exist for resolving the strain energy and static frictional forces along the length of a deformed nanotube supported on a substrate. We present a method using nonlinear elastic rod theory in which we compute the flexural strain energy and static frictional forces along the length of single walled carbon nanotubes (SWCNTs) manipulated into various shapes on a clean SiO 2 substrate. Using only high resolution atomic force microscopy images of curved single walled nanotubes, we estimate flexural strain energy distributions on the order of attojoules per nanometer and the static frictional forces between a SWCNT and SiO 2 surface to be a minimum of 230 pN nm −1 .

This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information.Strus, Mark C.; Cano, Camilo I.; Pipes, R. Byron; Nguyen, Cattien V.; and Raman, Arvind, "Interfacial energy between carbon nanotubes and polymers measured from nanoscale peel tests in the atomic force microscope" (2009 b s t r a c tThe future development of polymer composite materials with nanotubes or nanoscale fibers requires the ability to understand and improve the interfacial bonding at the nanotube-polymer matrix interface. In recent work [Strus MC, Zalamea L, Raman A, Pipes RB, Nguyen CV, Stach EA. Peeling force spectroscopy: exposing the adhesive nanomechanics of one-dimensional nanostructures. Nano Lett 2008;8(2):544-50], it has been shown that a new mode in the Atomic Force Microscope (AFM), peeling force spectroscopy, can be used to understand the adhesive mechanics of carbon nanotubes peeled from a surface. In the present work, we demonstrate how AFM peeling force spectroscopy can be used to distinguish between elastic and interfacial components during a nanoscale peel test, thus enabling the direct measurement of interfacial energy between an individual nanotube or nanofiber and a given material surface. The proposed method provides a convenient experimental framework to quickly screen different combinations of polymers and functionalized nanotubes for optimal interfacial strength.Published by Elsevier Ltd.