Interfacial layer structure

The polymerization process was firstly monitored by tensiometry (Figure 1). At the beginning no surface pressure was measured indicating that coniferyl alcohol is not surface active. After peroxidase and hydrogen peroxide spreading, the surface pressure increases indicating the formation of an interfacial layer. After 6-8 hours, the surface pressure levels off around 9 mN/m and then tends to decrease. This behaviour can be explained by a desorption of the molecules from the interface to the bulk or by a change of the interfacial layer structure. 

Oscillations may exert a strong effect on adsorption processes in the frictional contact. Adsorption of particles on the electrode with a certain potential is known [23] to occur at a finite speed. Under low oscillation frequencies the adsorption manages to follow the potential and participate in the variation of the interfacial layer structure. At high frequencies the adsorption mechanism does not work, giving place to electrostatic charging of the layer as a condenser, i.e. the generation of the double electric layer (DEL). A mechanical model of the interfacial DEL has been elaborated by Shepenkov [24]. It follows from the model that, if a periodic mechanical force acts on the double layer from the side of the liquid or electrode, the electrode potential will vary periodically with the same excitation frequency. 

Thus, the previously used nanoscopic method allows the estimation of both special features in the interfacial layer structure in pol5mer nanocomposites and, its sizes and properties. For the first time it has been shown, that in elastomeric particulate-filled nanocomposites two consecutive interfacial layers are formed, which are a reinforcing element for the indicated nanocomposites. The proposed theoretical method of interfacial layer thickness estimation, elaborated within the framewoiks of fractal analysis in experimental works. 

A cross-sectional transmission electron microscopy (TEM) image of a material with predetermined morphology of spherical pores was examined. The structure consists of an interfacial layer, structural layer, and a substrate. The substrate is in direct mechanical contact with the interfacial layer. The structural layer is composed of spherical nanopores nanostructure, and essentially consists of the cross-linkable polymer. The interfacial layer lacks the spherical nanopores. The thickness of the interfacial layer is 2-30 nm. The structural layer thickness is of the range 50-300 nm. 

Variation e defines corresponding change of interfacial layer structure characterized by its fractal dimension d j as well. Between parameters e, d and d j intercommunication exists, expressed by the relationship [13] ... 

It is intriguing that upon emersion the value of A0 changes up to about 0.3 V compared with the immersed state.41 This has been attributed42,51 to the different structure of the liquid interfacial layer in the two conditions. In particular, the air/solvent interface is missing at an emersed electrode because of the thinness of the solvent layer, across which the molecular orientation is probably dominated by the interaction with the metal surface. 

The extent of perturbation brought by a change in temperature in the interfacial layer is expected to depend on the structure of the layer itself. In other words, dEa /dT must depend in some way on AX. This point has been discussed at length by Trasatti26,32,76 in previous papers and only some recent aspects will be illustrated here. 

The effect of the phospholipids on the rate of ion transfer has been controversial over the last years. While the early studies found a retardation effect [6-8], more recent ones reported that the rate of ion transfer is either not retarded [9,10] or even enhanced due to the presence of the monolayer [11 14]. Furthermore, the theoretical efforts to explain this effect were unsatisfactory. The retardation observed in the early studies was explained in terms of the blocking of the interfacial area by the phospholipids, and therefore was related to the size of the transferring ion and the state of the monolayer [8,15]. The enhancement observed in the following years was attributed to electrical double layer effects, but a Frumkin-type correction to the Butler Volmer (BV) equation was found unsuitable to explain the observations [11,16]. Recently, Manzanares et al. showed that the enhancement can be described by an electrical double layer correction provided that an accurate picture of the electrical double layer structure is used [17]. This theoretical approach will be the subject of Section III.C. 

The kinetics of an enzyme catalysed reactions in a w/o-microemulsions is dependent on several parameters. For example, the substrates and enzymes distribute within the different parts of a one-phase microemulsion with different concentrations. The enzymes are located in the water and hydrophobic substrates are mainly dissolved in the oil. Additionally, the choice of oil and surfactant, the water concentration, and the structure of the interfacial layer can influence the activity and stability of biocatalysts. The influences of the main parameters on the kinetics will be discussed in this chapter. 

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