Lateral force microscopy measurement

Several studies on thin polymer films also indicated a sub-T Arrhenius-type relaxation process, which was related to the motion within a distinct surface layer of higher mobility or to increased heterogeneity [35, 44, 63, 64], yielding Ea 100 kJ/mol [44] and Ea = 185 3 kJ/mol [14]. Lateral force microscopy measurements on thin PS films [63] found a thickness dependent surface y -relax-ation process, with Ea = 55 kJ/mol for a 65 nm thick film. Fast sub-T -relaxations at surfaces of thin polymer films were measured by AFM, including the relaxation of... 

In 1987 Mate et al. [468] used, for the first time, an atomic force microscope (AFM) to measure friction forces on the nanometer scale (review Ref. [469]). This technique became known as friction force microscopy (FFM) or lateral force microscopy (LFM). To measure friction forces with the AFM, the fast scan direction of the sample is chosen perpendicular to the direction of the cantilever. Friction between the tip and the sample causes the flexible cantilever to twist (Fig. 11.7). This torsion of the cantilever is measured by using a reflected beam of light and a position-sensitive detector in the form of a quadrant arrangement of photodiodes. This new method made it possible for the first time to study friction and lubrication on the nanometer scale. 

Abstract. Quantitative measurements of lateral force required for displacement of SWNTs bundle on the surface of highly oriented pyrolytic graphite with the help of atomic force microscope (AFM) were performed in real time . New method of quantitative calibration of lateral forces was used for interpretation results of lateral force microscopy (LFM). It allows us to receive numerical values of adhesion force of bundle to substrate easy and without specific equipment. 

The quality of the gradient was observed by contact angle measurements, infrared spectroscopy, XPS, ellipsometry, and lateral force microscopy. 

We find that a finite roughness of the calcite surface must be included to achieve quantitative agreement between the calculated and experimental reflectivities. We use the model described in Equation (20) (Robinson 1986) that assumes that the roughness is the result of individual monatomic steps within the (approximately micrometer-sized) lateral coherence length of these measurements. We found a surface roughness of 1.1 A. Independent atomic force microscopy measurements have shown that the step density of these calcite cleavage surfaces is very small (Sturchio et al. 1997). 

The variations in friction between the tip and sample causes a stick and slip movement of the lever s tip. If the fast scan direction (jc) is perpendicular to the lever axis this results in lever torsion. Deflection of the light beam by a twisted lever on the position sensitive detector is perpendicular to the usual deviation stemming from normal (z) forces. Thereby, discrimination of Fx and F is possible. Lateral force microscopy (LFM) measures the forces parallel to the surface plane. The feedback loop must be slowed down, as always when a force channel is measured. 

LFM Lateral force microscopy (frictional measurements of surfaces based upon a tip s lateral and torsional response)... 

Lateral force microscopy (LFM) measures the lateral deflections in the cantilever that are present from forces on the cantilever parallel to the plane of the sample surface. Lateral deflections of the cantilever are normally attributable to changes in surface friction or changes in slope. The LFM has been used to image variation in surface friction which can arise from inhomogeneity in the surface material. 

As early as 1996, it was noted that Ti3SiC2 shavings had a graphitic feel to them [4], and this was later confirmed [168] when the friction coefficient, p, of Ti3SiC2 basal planes was measured using lateral force microscopy and shown to be one of the lowest ever reported, at 2-5 x 10. Not only was this value exceptionally low, but it remained very low during up to six months exposure to the atmosphere. 

Lateral force microscopy (LFM) This mode measures the frictional forces on a surface. By measuring the twist of the cantilever, rather than merely its deflection, one can qualitatively determine areas of higher and lower friction. 

The present study aims to understand the influence of solvent quality on the molecular-level friction mechanism of tethered, brushlike polymers. It involves complementary adsorption studies of PLL-,g-PEG by means of optical waveguide lightmode spectroscopy (OWLS) and quartz crystal microbalance with dissipation (QCM-D) as well as friction studies performed on the nanoscale using colloidal-probe lateral force microscopy (LFM). The adsorbed mass measured by QGM-D includes a contribution from solvent molecules absorbed within the surface-bound polymer fllm. This is in contrast to optical techniques, such as OWLS, which are sensitive only to the dry mass of a polymer adsorbed onto the surface of the waveguide.By subtracting the dry mass , derived from OWLS measurements, from the wet mass , derived from QCM-D measurements, it is therefore possible to determine the mass of the solvent per unit substrate area absorbed in the brushlike structure of PLL- -PEG, expressed as areal solvation, P. Areal solvation was varied by choosing solvents (aqueous buffer solution, methanol, ethanol, and 2-propanol) of different quality with respect to the PEG brush. The solvents were characterized in terms of the three-component Hansen solubility parameters, and these values were compared with measured areal solvation of the PEG brush. 

In this article, we aim to introduce our recent investigation relating to the surface molecular aggregation structure and surface molecular motion of the flu-oro(co)polymers with Rf side group. GI-WAXD measurement and X-ray photoelectron spectroscopy (XPS) using Cgo ion beam were applied to the surface molecular aggregation structure analysis and the depth analysis of the fluoropolymer films, respectively. Temperature dependence of the dynamic contact angle, XPS measurement in pseudo-hydrated state, and lateral force microscopy (LFM) measurement... 

Lateral Force Microscopy (LFM) measures the lateral deflections in the cantilever that are present from forces... 

Chemical force microscopy (CFM) refers to the chemical modification of the AFM tip with specific functional groups to measure the forces involved in chemically specific interactions with a surface. It is implemented in lateral force microscopy, force spectroscopy (force curve), and force-... 

In friction force microscopy (also called lateral force microscopy, LFM), on the contrary, these lateral forces are measured and may yield important insight into friction forces, their dependence on particular phases, and orientation of the underlying polymer or environmental conditions. Due to the difficulties in obtaining truly quantitative friction force data and the dependence of friction forces on load and scan velocity (due to the time-temperature superposition principle) [14], which all require tedious experimental procedures, friction force microscopy is not widely used in the analysis of polymer morphologies. 

Polymeric materials exhibit viscoelastic phenomena, which must be taken into account in designing the materials applications. For example, rubber in a tire receives stimuli over a wide frequency and temperature range from the road surface. In the case of bulk samples, the frequency and temperature can be converted mutually based on the time-temperature superposition (TTS) principle [72]. However, TTS is a kind of empirical rule and, consequently, an actual measurement method with a wide frequency and temperature range is necessary to precisely predict the properties of practical products. Various AFM-based conventional methods have been proposed to measure viscoelasticity such as lateral force microscopy (LFM) [73-75], force modulation (FM) [76-78], and contact resonance (CR) [79-81]. Even tapping mode can report energy-dissipative phenomena [44,82-84] and further offers loss tangent mapping [85,86]. 

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