Specific component of surface free

Table 8 Specific Components of Surface Free Energy of Adsorption of MSX, SX-I, and SX-I... 

Polar probes have both dispersive and specific components of surface free energy of adsorption. The specific component of surface free energy of adsorption (AGa is determined by subtracting the dispersive contribution from the total free energy of adsorption, and can be obtained from the vertical distance between the alkane reference line [Eq. (30) Figure 21] and the polar probes of interest according to the following equation (60) ... 

Authors of Ref. [49] proved that the variation of the term RT In Vn as a function of the molar deformation polarization of n-alkanes Pdp is a straight line which slope equal to C Pds is proportional to the surface ability for dispersive interactions. AG = 0 is defined in the same way as in the case of Saint Flour-Papirer s method. However, in this procedure AG = 0 values are always positive while in approach [48] the negative values of the specific component of the free energy of adsorption were observed. Later, Donnet et al. [29] observed that their earlier proposal (i.e. that from Ref.[49]) based on the fundamental London equation gives only a first approximation of the ionization energy of a molecule. They proposed to use Eq.(15) in the form ... 

If RTlnV is plotted versus a(yL ) for a series of alkanes a straight line results and the dispersive contribution of the surface energy can be calculated from the slope. If polar probe molecules are injected, specific interactions can be determined. In the above-mentioned plot, points representing a polar probe are located above the straight line. The distance is equal to the specific component of the free energy JG /. (equation 5). 

Inverse gas chromatographic measurements may be carried out both at infinite dilution and at finite solute concentrations [1]. In the first case vapours of testing solutes are injected onto the colurtm and their concentrations in the adsorbed layer proceed to zero. Testing substances interact with strong active sites on the examined surface. The retention data are then converted into, e.g. dispersive component of the surface free energy and specific component of free energy of adsorption. In the second case, i.e. at finite solute concentrations, the appropriate adsorption isotherms are used to describe the surface properties of polymer or filler. The differential isosteric heat of adsorption is also calculated under the assumption that the isotherms were obtained at small temperature intervals. 

Finally, there are several approaches to determine the specific component of the surface free energy of carbon materials [71-73]. Among these, that proposed by Donnet et al [73] uses the standard adsorption free energy which is plotted against (hr L) o-10 , where h is the Planck constant, is the characteristic vibration frequency of the electron and a is the deformation polarizability. The method seems to provide reasonable results, although it does not take into account the effect of the surface irregularities. 

Specific Component of the Surface Free Energy of Heat-Treated Silicas. Specific interaction capacities of heat-treated silicas, that is, their ability to interact with polar molecules, were examined with chloroform (Lewis acid probe) and toluene and benzene (amphoteric molecules). Figure 2 provides examples of the evolution of the specific interaction parameter Zsp of the different silicas with chloroform as a probe. 

Specific Component of the Surface Free Energy of Heat-Treated Silicas... 

All other polar probes exhibit higher net retention volumes, En. and the difference between their net retention volume and that of the n-alkanes for the same value of the dispersive component of surface energy leads to the value of the free energy of desorption, AGjp, corresponding to the specific acid-base interaction, expressed as ... 

The pharmaceutical literature has discussed the mechanical aspects of the tablet making process but has rarely discussed it from a surface chemistry or adhesion science perspective. In this paper, we discuss a model based on surface chemical principles that can be used to calculate the tensile strength of tablets from constituent components. Specifically, the role of surface free... 

Fig. la —c. Schematic drawing of some specific examples of polymer molecules at an interface (a) the free surface of a homopolymer, (b) the surface enrichment of one component in a miscible polymer blend, and (c) the interface between polymers of different molecular weight and/or chemical composition... 

The electrical double layer has been studied at the interface of acidified (pH = 3) KCIO4 and K2SO4 solutions in contact with an Sn solid drop electrode with an additionally remelted surface (SnDER).616 The E, is independent of ctl as well as of the electrolyte. Weak specific adsorption of CIO4 at SnDER is probable around <7 = 0. This view is supported by the high value of/pz for SnDER/H20 + KCIO4 (fpz = 1 -27). A value of fpz = 0.99 for SnDER/H20 + K2S04 indicates that the surface of SnDER is geometrically smooth and free from components of pseudo-capacitance.616... 

The use of reactive surfaces for the specific synthesis of biomolecules, or as a model for replication processes, was first reported by Cairns-Smith and Weiss (see Sect. 7.1) and continued by G. Wachtershauser (see Sect. 7.3), as well as J. Ferris and L. Orgel. It was thus appropriate to study the stabilisation of the reaction partners in enzyme-free self-replication at surfaces with reactive properties. As early as 1995, the group of G. von Kiedrowski (then at Freiburg, Germany) bonded reacting molecules at surfaces and then added the other required reaction components to the system in a stepwise manner (the latter process is referred to as feeding ). 

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