Interfacial dynamics

In recent years, advances in experimental capabilities have fueled a great deal of activity in the study of the electrified solid-liquid interface. This has been the subject of a recent workshop and review article [145] discussing structural characterization, interfacial dynamics and electrode materials. The field of surface chemistry has also received significant attention due to many surface-sensitive means to interrogate the molecular processes occurring at the electrode surface. Reviews by Hubbard [146, 147] and others [148] detail the progress. In this and the following section, we present only a brief summary of selected aspects of this field. 

CR 3nd tp are the contributions from chain recoiling and interfacial dynamics (i.e. drag forces and disentanglement), respectively, and / ve is the viscoelastic loss function which has interfacial and bulk parts. / is a characteristic length of the viscoelastic medium, t is the contact time and n is the chain architecture factor. Fig. 21 illustrates the proposed rate dependency of adhesion energy. 

Based on the arguments presented thus far, it would seem that, for a given PSA, the work of adhesion, and thus the peel force, should decrease systematically as the surface energy of the release coating is decreased. Therefore, fluorochemical containing polymers should provide the lowest release forces. In practice, these generalities often do not hold, due to other factors, such as interfacial dynamics and rheological considerations. 

Kinetics of chemical reactions at liquid interfaces has often proven difficult to study because they include processes that occur on a variety of time scales [1]. The reactions depend on diffusion of reactants to the interface prior to reaction and diffusion of products away from the interface after the reaction. As a result, relatively little information about the interface dependent kinetic step can be gleaned because this step is usually faster than diffusion. This often leads to diffusion controlled interfacial rates. While often not the rate-determining step in interfacial chemical reactions, the dynamics at the interface still play an important and interesting role in interfacial chemical processes. Chemists interested in interfacial kinetics have devised a variety of complex reaction vessels to eliminate diffusion effects systematically and access the interfacial kinetics. However, deconvolution of two slow bulk diffusion processes to access the desired the fast interfacial kinetics, especially ultrafast processes, is generally not an effective way to measure the fast interfacial dynamics. Thus, methodology to probe the interface specifically has been developed. 

The overall picture arising from a comprehensive view of the solvation dynamics studies at interfaces that have been done can be summarized interfacial dynamics differ from bulk solution and cannot simply be considered the same as the bulk. In most cases, the structure of the interface appears to impact the dynamics by slowing them down. However, in a few cases, the dynamics appear to speed up. 

Interfacial Dynamics Corporation, Portland, Oregon, USA Roy W. Hughes... 

Inner slip, between the solid wall and an adsorbed film, will also influence the surface-liquid boundary conditions and have important effects on stress propagation from the liquid to the solid substrate. Linked to this concept, especially on a biomolecular level, is the concept of stochastic coupling. At the molecular level, small fluctuations about the ensemble average could affect the interfacial dynamics and lead to large shifts in the detectable boundary condition. One of our main interests in this area is to study the relaxation time of interfacial bonds using slip models. Stochastic boundary conditions could also prove to be all but necessary in modeling the behavior and interactions of biomolecules at surfaces, especially with the proliferation of microfluidic chemical devices and the importance of studying small scales. 

Interfacial chemistry of dissolving metal oxide particles Dissolution by organic acids. Chap. 14 p. 513-540, Interfacial dynamics (Ed. N. Kallay) Marcel Dekker N.Y. Sampson, C.F. (1969) The lattice parameters of natural single crystal and synthetically produced goethite (a-FeOOH). Acta Cryst. B 25 1683-1685... 

In this chapter, the development of a mesoscopic modeling formalism is presented in order to gain fundamental insight into the structure-wettability influence on the underlying liquid water transport and interfacial dynamics in the PEFC CL and GDL. 

The studies presented here illuminate just a few of the exciting possibilities for the use of VSFS to study chemistry at liquid/liquid surfaces. Solvents and adsorbates can be probed and orientations and conformations obtained. Molecular dynamics has recently been employed to gain additional information using the constraints provided by the spectroscopy. The future of this technique lies in expanding the spectrum to longer wavelengths so that more vibrations can be probed in each molecule and more complicated molecules can be studied. The study of interfacial dynamics will also offer exciting opportunities for the future. 

FIGURE 11.7 Ordered arrays formed from filtered latex suspensions (Photo from Interfacial Dynamics Corporation, Portland, Oregon. Reprinted with permission.)... 

Taylor and Girault [154], and has been further developed by Girault and coworkers [155], Vanysek and Hernandez [156] and Mare k et al. [149]. The use of a microscopic interface is an essential requirement for a fluctuation analysis of ion transfer system under thermodynamic equilibrium which was attempted first by Marecek et al. [149]. No kinetic data have been reported from voltammetric or noise measurement at microliquid interfaces, though a new insight into the interfacial dynamics comprising ion transfer has been thought possible [149]. 

Interfacial Dynamics www.idclatex.com Nissan Chemicals www.snowtex.com... 

Harmonic interfacial disturbances can be induced by bringing an air bubble at the tip of a capillary in oscillation by a piezoelectric excitation system. In more modem Instmments pressure variation in the bubble is directly monitored by pressure transducers. Such a set-up allows the determination of Interfacial dynamic moduli. 

Kallay, Nikola. Interfacial Dynamics. Surfactant Science Series, vol. 88. New York Marcel Dekker, 2000. 

Salfity, J.A., Regazzoni, A.E., and Blesa, M.A., Interfacial chemistry of dissolving metal oxide particles Dissolution by organic acids, in Interfacial Dynamics, Kallay, N., ed., Marcel Dekker, New York, 1999, p. 513. 

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