Atomic force microscopy adhesion studies

In a recent case study (see Svendsen et al, 2007 and also Problem 6.1), in collaboration with a paint company, the adhesion of six different epoxies-silicon systems has been studied. These paints are used in marine coating systems. Some epoxies showed adhesion problems in practice while others did not. The purpose of the study was to understand the origin of these problems and whether adhesion could be described/ correlated to surface characteristics, e.g. surface tensions. An extensive experimental study has been carried out including both surface analysis (contact angle measurements on the six epoxies, surface tension of silicon at various temperatures, atomic force microscopy (AFM) studies of the epoxies), as well as measurements of bulk properties (pull-off adhesion tests and modulus of elasticity). Theoretical analysis included both estimation of Zisman s critical surface tensions and surface characterization using the van Oss-Good theory. 

Carpick, R.W., The study of contact, adhesion, and friction at the atomic scale by atomic force microscopy. University of Califomia-Berkeley, Berkeley, CA, 1997. 

Hayes, R.A. and Ralston, J., Application of atomic force microscopy in fundamental adhesion studies. In Mittal, K.L. and Pizzi, A. (Eds.), Adhesion Promotion Techniques — Technological Applications. Dekker, New York, 1999, pp. 121-138. 

Atomic force microscopy [6, 7] is one of the most suitable methods for research carbon nanotubes. AFM allows to receive not only a relief of the studied sample, but also distribution of mechanical characteristics, electric, magnetic and other properties on its surface. With the help of AFM, controllable manipulation of individual CNTs and CNTs bundles became possible. In this paper we report our approach to manipulating SWCNTs bundles with lateral force microscopy. LFM gives possibility to study lateral forces that probe acts upon bundles. In spite of good visualization of LFM, its lack is absence of reliable techniques of quantitative interpretation of results. The new way of calibration developed ourselves has allowed to pass from qualitative estimations to quantitative investigations [8], The given calibration technique is much more exact, than others known till now [9, 10], and does not assume simplification. With the help of new technique we may study adhesion of bundles to substrate and adhesion of CNTs in bundle qualitatively in real time more easy way. This result will provide new possibilities for nanotube application. 

Hooton JC, German CS, Allen S, et al. An atomic force microscopy study of the effect of nanoscale contact geometry and surface chemistry on the adhesion of pharmaceutical particles. Pharm Res 2004 21(6) 953-961. 

The surface of the pentacene film was examined by atomic force microscopy (AFM). It exhibits crystallites with a diameter of about 250 run in the transistor channel. On the gold surface of the drain and source contacts, the dimensions are twice the size as on silicon dioxide. In comparison with growth studies in [18] where the surface was pretreated by an adhesion promoter, the presented pentacene film consists of very small crystallites. 

Physical characterization of macromolecular systems strives to determine chemical structure/property relationships. This subfield includes study of thermomechanical performance viscoelastic properties surface properties, adhesion science thermal transitions morphological analysis, including semicrystalline, amorphous, liquid-crystalline, and microphase-separated structures. Structural analysis employs electron microscopy, con-focal microscopy, optical microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and x-ray and neutron scattering of macromolecular compositions. 

Force spectroscopy, though originally conceived as a tool for calibrating the atomic force microscope, has become an invaluable tool for studying adhesive interactions on the nanometer scale [29 - 31]. In force spectroscopy the deflection of an atomic force microscopy (AFM) tip is measured as a sample is moved into and then out of contact with the tip. The characteristic hysteresis observed as the sample is retracted is due to adhesion between the tip and sample. The point at which the adhesion is broken and the AFM tip pulls off the sample surface is characterized by a sharp discontinuity in the... 

E. Meyer, H. Heinzelmann, P. Griitter, T. Jung, H.R. Hidber, R. Rudin, and H.J. Giintherodt. Atomic Force Microscopy for the Study of Tribology and Adhesion. Viin Solid Films 181 527 (1989). 

Atomic force microscopy is considered one of the most perspective methods for stud5ring polymer blends is because this method allows to clearly define the phase boundary and its scale. Polymer identification was performed by controlling the interaction of the probe with the sample surface at different points. When approaching the strrface of the cantilever is deflected downward (to the sample) due to attractive forces imtil the probe comes into contact with the sample. When the probe is withdrawn from the studied surface, a hysteresis is observed, associated with the adhesive forces. Adhesion forces between the probe and the sample are forcing them to remain in contact, which causes the cantilever to bend. Phase of... 

Zhang, H., Grim, P. C. M., Vosch, T., Wiesler, U.-M., Berresheim, A. J., MuUen, K., and De Schryver, F. C. 2000. Discrimination of dendrimer aggregates on mica based on adhesion force A pulsed mode atomic force microscopy study, Langmuir 16, 9294-9298. 

Atomic force microscopy (AFM) and electrochemical atomic force microscopy (ECAFM) have proven usefiil for the study of nucleation and growth of electrodeposited CP films on A1 alloy [59]. AFM was used to study adhesion between polypyrrole and mild steel [60], whereas electric force microscopy (EFM) has been used to study local variations in the surface potential (work function) of CP films [61]. AFM with a conductive tip permits a nanoscale AC impedance measurement of polymer and electrolyte interfaces, permitting differentiation between highly conductive amorphous regions and less-conductive crystalline regions of the CP film [62]. 

A detailed study on the topography of elastic and adhesive properties of individual wood-derived CNCs using atomic force microscopy (AFM) was made by Lahiji et al. [59]. The AFM experiments involving high-resolution dynamic mode imaging and jump-mode measurements were performed on individual CNCs imder ambient conditions with 30% relative humidity (RH) and under a N atmosphere with 0.1% RH. The transverse elastic... 

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