Polymer Characterization with the Atomic Force Microscope (original) (raw)
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Atomic force microscopy and direct surface force measurements
Pure and Applied Chemistry, 2005
Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.
Atomic force microscopy and direct surface force measurements (IUPAC Technical Report
Pure and Applied Chemistry, 2005
Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.
A Simple and Effective Method of Evaluating Atomic Force Microscopy Tip Performance
Langmuir, 2001
The morphology of a surface imaged by dynamic force mode atomic force microscopy is obtained through an interaction between the probe tip and surface features. When the tip is contaminated and the size of the contaminant is comparable to the size of the features on the sample surface, artifacts attributable to the contaminant are observed to dominate the image. To reduce the possibility of effects from such artifacts, the tip performance should be checked by scanning a reference sample of known surface morphology. We demonstrate a simple and effective method of evaluating tip performance by the imaging of a commercially available biaxially oriented polypropylene (BOPP) film, which contains nanometer-scale-sized fibers. This sample is appropriate for use as a reference because a contaminated tip will not detect the fiberlike network structure. In addition, BOPP has a soft, highly hydrophobic surface of low surface energy, thus ensuring that the tip will not be damaged or contaminated during the evaluation process.
Effect of Tip Size on Force Measurement in Atomic Force Microscopy
Langmuir, 2008
An atomic force microscope (AFM) has been used to study solvation forces at the solid-liquid interface between highly oriented pyrolytic graphite (HOPG) and the liquids octamethylcyclotetrasiloxane (OMCTS), n-hexadecane (n-C 16 H 34), and n-dodecanol (n-C 11 H 23 CH 2 OH). Oscillatory solvation forces (F) are observed for various measured tip radii (R tip) 15-100 nm). It is found that the normalized force data, F/R tip , differ between AFM tips with a clear trend of decreasing F/R tip with increasing R tip .
Study of tip–sample interaction in scanning force microscopy
Applied Surface Science, 2000
The study of the tip-sample interaction has been achieved combining the simultaneous measurement of force, resonance frequency, oscillation amplitude and quality factor vs. distance curves. From the analysis of these experiments performed in Ž . air with cantilevers of low force constant -0.75 Nrm , we propose that the tip jumps to contact due to the formation of a liquid neck between tip and sample. Besides, a few nanometers before the tip jumps to contact, a decrease in oscillation amplitude is detected. We observe that this decrease is mainly caused by a dissipative interaction. By selecting this interaction as feedback signal, the scanning force microscope can be operated in the non-contact regime. q
Atomic force microscopy is a convenient and exceptionally rich source of information about materials on the nano-scale. The instrument can be configured to operate in a large number of modes. The main task of AFM is to produce reliable and repeatable measurement of surface and intermolecular forces, which are needed for surface analysis and provide plentiful of information regarding other features of specimen. These diverse modes measure different atomic forces that are acting between apex and specimen surface and are used for producing topographical image of the sample with high molecular resolution. The force measurement is by way of cantilever deflection measures. The cantilever can be made by piezoelectric material, whereas it is a piezoelectric stage that moves the specimen with respect to the tip. The cantilever is affected by position, tip-sample separation, it’s material, and different forces. A beam of laser focused on the force sensing/imposing lever and reflected onto a sensitive detector which is position sensing photo diode PSPD. Due to high resolution and small contact areas there is no need of vacuum and problems due to contamination and roughness are minimized.
The atomic force microscope (AFM) has previously been applied to the measurement of surface forces (including adhesion and friction) and to the investigation of material properties, such as hardness. Here we describe the modification of a commercial AFM that enables the " stiffness " of interaction between surfaces to be measured concurrently with the surface forces. The stiffness is described by the rheological phase difference between the response of the AFM tip to a driving oscillation of the substrate. We present the interaction between silica surfaces bearing adsorbed polymer, however, the principles could be applied to a wide variety of materials including biological samples.
Probing surfaces with single-polymer atomic force microscope experiments
Biointerphases, 2006
In the past 15 years atomic force microscope ͑AFM͒ based force spectroscopy has become a versatile tool to study inter-and intramolecular interactions of single polymer molecules. Irreversible coupling of polymer molecules between the tip of an AFM cantilever and the substrate allows one to study the stretching response up to the high force regime of several nN. For polymers that glide or slip laterally over the surface with negligible friction, on the other hand, the measured force profiles exhibit plateaus which allow one to extract the polymer adsorption energies. Long-term stable polymer coatings of the AFM tips allow for the possibility of repeating desorption experiments from solid supports with individual molecules many times, yielding good sampling statistics and thus reliable estimates for adsorption energies. In combination with recent advances in theoretical modeling, a detailed picture of the conformational statistics, backbone elasticity, and the adsorption characteristics of single polymer molecules is obtained.
Tip-Sample Forces in Atomic Force Microscopy: Interplay between Theory and Experiment
MRS Proceedings, 2013
ABSTRACTSeveral examples of Atomic Force Microscopy imaging in the oscillatory resonant and non-resonant modes are analyzed with a theoretical description of tip-sample force interactions. The problems of high-resolution imaging and compositional mapping of heterogeneous polymers are considered. The interplay with theory helps the experiment optimization and rational understanding of the image contrast.