Atomic force microscopy components

Dang, J. M. C., Braet, F., and Copeland, L. (2006). Nanostructural analysis of starch components by atomic force microscopy. /. Microsc. 224,181-186. 

The experimental techniques described above of charge—discharge and impedance are nondestructive. Tear-down analysis or disassembly of spent cells and an examination of the various components using experimental techniques such as Raman microscopy, atomic force microscopy, NMR spectroscopy, transmission electron microscopy, XAS, and the like can be carried out on materials-spent battery electrodes to better understand the phenomena that lead to degradation during use. These techniques provide diagnostic techniques that identify materials properties and materials interactions that limit lifetime, performance, and thermal stabiity. The accelerated rate calorimeter finds use in identifying safety-related situations that lead to thermal runaway and destruction of the battery. 

Transmission electron microscopy (TEM) has traditionally been the mainstay of morphological investigations of polyolefins [8], but recent developments in low voltage high-resolution field emission gun scanning electron microscopy (FEG-SEM) [9] and the advent of atomic force microscopy (AFM) and related near-field techniques [10] have challenged its dominance at the length scales of the order of 10 nm, characteristic of both microdeformation (cavitation, fibrils) and structural components of semicrystalline... 

IPNs are also attractive for development of materials with enhanced mechanical properties. As PDMS acts as an elastomer, it is of interest to have a thermoplastic second network such as PMMA or polystyrene. Crosslinked PDMS have poor mechanical properties and need to be reinforced with silica. In the IPNs field, they can advantageously be replaced by a second thermoplastic network. On the other hand, if the thermoplastic network is the major component, the PDMS network can confer a partially elastomeric character to the resulting material. Huang et al. [92] studied some sequential IPNs of PDMS and polymethacrylate and varied the ester functionalities the polysiloxane network was swollen with MMA (methyl methacrylate), EMA (ethyl methacrylate) or BuMA (butyl methacrylate). Using DMA the authors determined that the more sterically hindered the substituent, the broader the damping zone of the IPN (Table 2). This damping zone broadness was also found to be dependant on the PDMS content, and atomic force microscopy (AFM) was used to observe the co-continuity of the IPN. 

Chen et al. [67,68] further extended the study of binary blends of ESI over the full range of copolymer styrene contents for both amorphous and semicrystalline blend components. The transition from miscible to immiscible blend behavior and the determination of upper critical solution temperature (UCST) for blends could be uniquely evaluated by atomic force microscopy (AFM) techniques via the small but significant modulus differences between the respective ESI used as blend components. The effects of molecular weight and molecular weight distribution on blend miscibility were also described. 

The materials analyzed were blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) in various ratios. The two components are miscible in all proportions at ambient temperature. The photooxidation mechanisms of the homo-polymers PS and PVME have been studied previously [4,7,8]. PVME has been shown to be much more sensitive to oxidation than PS and the rate of photooxidation of PVME was found to be approximately 10 times higher than that of PS. The photoproducts formed were identified by spectroscopy combined with chemical and physical treatments. The rate of oxidation of each component in the blend has been compared with the oxidation rate of the homopolymers studied separately. Because photooxidative aging induces modifications of the surface aspect of the material, the spectroscopic analysis of the photochemical behavior of the blend has been completed by an analysis of the surface of the samples by atomic force microscopy (AFM). A tentative correlation between the evolution of the roughness measured by AFM and the chemical changes occurring in the PVME-PS samples throughout irradiation is presented. 

Figure 2.14 shows the components of the photosystems residing along the thylakoid membranes. Insights into the structure of the membrane and component architecture has recently been obtained by atomic force microscopy (Bahatyrova et ah, 2004). The space inside the membranes is called the lumen,... 

It is customarily assumed that the overall particle-particle interaction can be quantified by a net surface force, which is the sum of a number of independent forces. The most often considered force components are those due to the electrodynamic or van der Waals interactions, the electrostatic double-layer interaction, and other non-DLVO interactions. The first two interactions form the basis of the celebrated Derjaguin-Landau-Verwey-Overbeek (DLVO) theory on colloid stability and coagulation. The non-DLVO forces are usually determined by subtracting the DLVO forces from the experimental data. Therefore, precise prediction of DLVO forces is also critical to the determination of the non-DLVO forces. The surface force apparatus and atomic force microscopy (AFM) have been used to successfully quantify these interaction forces and have revealed important information about the surface force components. This chapter focuses on improved predictions for DLVO forces between colloid and nano-sized particles. The force data obtained with AFM tips are used to illustrate limits of the renowned Derjaguin approximation when applied to surfaces with nano-sized radii of curvature. 

The top panel of Fig. 3.2 presents a selection of results for the lateral organization of some simple one- and two-component lipid bilayers that have been investigated by computer-simulation calculations and atomic force microscopy. A pronounced degree of lateral heterogeneity in terms of lipid domains is found. The lipid domains are either solid hpid patches in fluid bilayers or fluid lipid patches in solid bilayers. In lipid mixtures, the domains may reflect incomplete phase separation. The sizes, the morphology, and the topology of the lipid domain patterns depend on the lipid composition and the thermodynamic conditions. The domains can be enhanced or suppressed by adding further lipid components or solutes [36]. 

The force between particles is the sum of a pH-independent van der Waals component, which is always attractive, and a pH-dependent electrostatic component, which can be attractive or repulsive. In Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the potential is used to calculate the interaction force or energy as a function of the distance between the particles. Atomic force microscopy (AFM) makes it possible to directly measure the force between the particles as a function of the distance, and commercial instruments are available to perform such measurements. Different approaches have been proposed to utilize the results obtained by AFM to determine the pHq. The quantity obtained by AFM corresponds to the lEP rather than the PZC. AFM was used to measure the force between SiO2 (negative potential over the entire studied pH range) and Si,N4 (lEP to be determined) in [681]. The pH at which the force at a distance of 17 nm was equal to zero was identified with the lEP. The van der Waals forces are negligible at such a distance, and the force is governed by an electrostatic interaction. The experimental results were consistent with DLVO theory. 

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