SUBSURFACE CHARACTERIZATION OF CARBON NANOTUBES IN POLYMER MATRIX USING ELECTRIC FORCE MICROSCOPY AND SCANNING ELECTRON MICROSCOPY
Minhua Zhao1,3, Bin Ming1, Xiaohong Gu2, Tinh Nguyen2, and Andr¨˘s E. Vlad¨˘r1
1,2National Institute of Standards and Technology, Gaithersburg, MD 20899
1Mechanical Metrology Division, 2Materials and Construction Research Division
3University of Maryland, IREAP, College Park, MD 20742
Scanning probe microscopy (SPM) and scanning electron microscopy (SEM) are two powerful techniques for the characterization of nanostructures on surfaces. With the emergence of nanotechnology, there is a growing need to characterize nanostructures under the surface of materials, especially in non-destructive ways. One application is studying the dispersion of carbon nanotubes (CNTs) within polymer composites. Traditionally this is beyond the capabilities of conventional SPM and SEM. Here we report on successful subsurface characterization of CNTs in polyimide composites using a special type of SPM named electric force microscopy (EFM), and the SEM. In the EFM, the contrast is based on long-range electrostatic interactions [1, 2]. In the SEM, there is a charge contrast at the interface of CNTs and the polymer . The optimal experimental parameters and the contrast mechanisms for EFM and SEM subsurface imaging on these samples were extensively studied. The highlights of this study were demonstrated by three dimensional reconstructions of CNTs embedded in a polymer matrix. These techniques open a new way to characterize high dielectric nanostructures in a low dielectric polymer matrix, which has a broad range of applications in nanotechnology.
1. Zhao, M.H., et al., Ultrasharp and high aspect ratio carbon nanotube atomic force microscopy probes for enhanced surface potential imaging. Nanotechnology, 2008, 19, 235704.
2. Zhao, M.H. et al, Development of quantitative electric force microscopy for subsurface characterization of carbon nanotubes in polymer composites. Nanotechnology, 2010, 21, 225702.
3. Zhao, M.H. et al., Subsurface characterization of high dielectric nanostructures in low dielelectric matrix using EFM and SEM. Nanotech 2010, Anaheim, paper # 884.