Interfacial force microscopy

Joyce, S.A. and Houston, J.E., A new force sensor incorporating force-feedback control for interfacial force microscopy. Rev. Sci. Instrum., 62(3), 710-715 (1991). 

Pasche, S. et al., Relationship between interfacial forces measured by colloid-probe atomic microscopy and protein resistance of polyfethylene glycol)-grafted poly(L-lysine) adlayers on niobia surfaces, Langmuir, 21, 6508, 2005. 

Thomas et al. [20] have measured adhesion forces between organic films over separations ranging from 10 nm to repulsive contact using interfacial force microscopy (IFM). 

Manne, S. and Gaub, H. E. 1997. Force microscopy Measurement of local interfacial forces and surface stresses, Curr Opin Colloid Interface Sci 2,145-152. 

Sigillo et al. (1997) used several experimental methods for the measurement of interfacial tension of a model polymer blend. Common to all methods presented here are two main points. The first is that a is obtained from experiments where the shape of the interface between the liquids is directly observed by means of optical microscopy techniques. The second point is that the interface geometry is controlled by a balance between the interfacial force and the viscous stresses generated by some flow applied to the system. Measurements have been carried out on a model polymer blend, whose constituents are a polyisobutylene and a polydimethylsiloxane, both transparent and liquid at room temperature. When compared with each other, the values of interfacial tension obtained from the different methods show a good quantitative agreement. Excellent agreement is also found with results for the same system previously published in the literature. 

In earlier nanotribological investigations using atomic force microscopy (AFM) (6, 7), a significant reduction in the interfacial friction measured between silicon oxide substrates and a sodium borosilicate microsphere was observed upon adsorption of PLL- -PEG on either one or both sides of the interface. In addition, an investigation of PLL- -PEG polymers, differing only in the PEG side-chain length, revealed that interfacial forces measured under aqueous con-... 

Relationship between Interfacial Forces Measured by Colloid-Probe Atomic Force Microscopy and Protein Resistance of Poly(ethylene glycoD-Grafted Poly(L-lysine) Adlayers on Niobia Surfaces... 

Measurement of interfacial forces thus offers the potential to study the factors involved in protein repellence or adsorption. Force measurements on adsorbed and grafted PEG layers have been reported, using both the surface forces apparatus (SFA) and the colloid-probe atomic force microscopy (AFM) technique. - Adsorbed PEG layers show responses due to relaxation processes,... 

Colloid Probe Atomic Force Microscopy. Colloid probe atomic force microscopy (AFM) uses a microsphere as a probe for the quantitative measurement of surface forces.The main advantage of using a microsphere instead of a sharp tip is the improved definition of the contact geometry and thus the ability to perform quantitative comparisons with theoretical models of interfacial forces. 

New chapter-opening photo presentation on interfacial force microscopy and how water wets a metal surface. Redesigned art and photography program captures the excitement of chemistry and includes integrated talking label system that aids student understanding of key concepts. 

The interaction between drops has been studied experimentally with different techniques [731]. The most important technique for studying interfacial forces across thin films is the thin film balance [699,732]. In fact, a whole class of thin film balances have been developed. They are described in detail in Sections 7.4 and 7.6. In another technique, two drops at the end of two capillaries are moved toward each other [733] or one drop is moved toward a planar interface [734]. The process is observed by optical microscopy. Direct force measurements have become possible with the atomic force microscope by attaching tiny oil drops to AFM cantilevers [270, 696]. Recently, such drops have also been produced in microfluidic channels [735]. 

Two decades have passed since the book by Jacob Israelachvili Intermolecular and Surface Forces" appeared. During this period, our knowledge on interfacial forces has significantly, improved partially due to new experimental tools and improved simulation capabilities. For example, the invention of scanning probe microscopy and the development of optical methods allow us to look at surface forces in much more detail. 

These authors doubt that such interactions can be estimated other than empirically without fairly accurate knowledge of the structure in the interfacial region. Sophisticated scattering, surface force, and force microscopy measurements are contributing to this knowledge however, a complete understanding is still a long way off. Even submonolayer amounts of adsorbed species can affect adhesion as found in metals and oxides [74]. 

Keywords. Hyperbranched macromolecules. Polymer films. Scanning force microscopy. Conformational transitions and interfacial ordering of single molecules... 

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