Interfacial thickness, evaluation

In a second study, they evaluated the interfacial thickness of twopoly(isoprene-b-methyl methacrylate) block copolymers (Pl-PMMA) using the same approach. Small-angle X-ray scattering experiments showed that films of the mixed diblock copolymers have a lamellar morphology with a spacing that varies with composition from 24 to 26 nm. Fluorescence decay profiles from these films were analyzed in terms of an energy transfer model that takes into account the distribution of junctions across the interface and calculated an interface thickness of 1.6 + — 0.1 nm. This value was independent of the acceptor/donor ratio (i.e., the acceptor concentration) in the films. 

SAXS is a more precise tool to quantitatively evaluate the two-phase structure of PU by providing the data of interdomain spacing, domain size, and interfacial thickness [40]. Figure 7.28 illustrated typical SAXS intensity profiles (/(S)S vs. 20) for PU/C20A nanocomposites. The one-dimensional correlation function F(Z) that is related to the electron density distribution within specimens is expressed as follows ... 

The temperature dependence of the interaction parameter for PS/PMMA and PS/styrene-acrylonitrile copolymer mixtures was measured by elHpsometry and evaluated from experimentally-found thickness of the interphase layer using Eq 6.18. It was found that the interfacial thickness increases with temperature. 

Analyzing the LS curve at the Porod region where I q) obeys the power law of / the interfacial thickness can be evaluated. If the interface is assumed by the sigmoidal curve defined as Gaussian with standard deviation o, the scattering at the Porod region can be expressed as [16]... 

By the total internal reflection condition at the liquid-liquid interface, one can observe interfacial reaction in the evanescent layer, a very thin layer of a ca. 100 nm thickness. Fluorometry is an effective method for a sensitive detection of interfacial species and their dynamics [10]. Time-resolved laser spectrofluorometry is a powerful tool for the elucidation of rapid dynamic phenomena at the interface [11]. Time-resolved total reflection fluorometry can be used for the evaluation of rotational relaxation time and the viscosity of the interface [12]. Laser excitation can produce excited states of adsorbed compound. Thus, the triplet-triplet absorption of interfacial species was observed at the interface [13]. 

No information is available in the published literature pertaining to the gas-liquid interfacial area, aL. It may be assumed that aL equals the disk area exposed to the air. The thickness of the liquid film on a vertically rotating disk partially immersed in a Newtonian liquid has been evaluated by Vijayraghvan and Gupta (1982). They also showed that the measured liquid holdup on the disk compares well with the values predicted from the flat-plate withdrawal theory. The gas-phase pressure drop is very low. The liquid and the gas phases are partially backmixed. The extent of backmixing is reduced by providing baffles. 

In this case, r(0) and the magic angle are calculated to be 0.4 and 54.7°, respectively. The thickness of a water/oil interfacial layer would be evaluated through TIR fluorescence anisotropy measurements and the value(s) provides information about characteristic features at a water/oil interface. 

Other than direct simulations of the adsorption isotherm, several methods for studying wetting are available. One can evaluate the fluid-solid interfacial tension from the expressions for the pressure tensor elements parallel to the surface that are analogous to equation (7) for the surface-normal pressure. (These methods are most reliable for featureless gas-solid potentials.) At the thin-film<=>thick film changeover, there will be a sharp change in the slope of the curve of surface tension versus Nads. 

If measurement of the areal density of connector molecules after fracture of the interface is not possible, it is possible to evaluate the areal density if the interfacial agent is deposited at the interface as a spin-coated thin film and no substantial diffusion away from the interface into the bulk materials is expected. In this case, a measurement by ellipsometry of the thickness of the film (spun using the same conditions) on a silicon substrate can be used to determine directly the nominal areal density of connector chains at the interface. In cases where the connectors can diffuse away from the interface during the annealing stage, however, this method will not give reliable results. 

A mean field theory has recently been developed to describe polymer blend confined in a thin film (Sect. 3.2.1). This theory includes both surface fields exerted by two external interfaces bounding thin film. A clear picture of this situation is obtained within a Cahn plot, topologically equivalent to the profile s phase portrait d( >/dz vs < >. It predicts two equilibrium morphologies for blends with separated coexisting phases a bilayer structure for antisymmetric surfaces (each attracting different blend component, Fig. 32) and two-dimensional domains for symmetric surfaces (Fig. 31), both observed [94,114,115,117] experimentally. Four finite size effects are predicted by the theory and observed in pioneer experiments [92,121,130,172,220] (see Sect. 3.2.2) focused on (i) surface segregation (ii) the shape of an intrinsic bilayer profile (iii) coexistence conditions (iv) interfacial width. The size effects (i)-(iii) are closely related, while (i) and (ii) are expected to occur for film thickness D smaller than 6-10 times the value of the intrinsic (mean field) interfacial width w. This cross-over D/w ratio is an approximate evaluation, as the exact value depends strongly on the... 

Evaluation of the meaningfulness of results from less sensitive and less selective methods needs additional attention (e.g. attenuated total reflectance infrared (ATR-IR) or solid-state NMR spectrometry) [2]. Indirect insights from functional studies include support for transmembrane orientation (Fig. 11.13b) from parabolic dependence of the activity of synthetic ion channel or pore on bilayer thickness (Section 11.3.7) [56] and other readouts in support of operational hydrophobic matching. Flippase activity may provide some support for interfacial location (Section 11.3.7, Fig. 11.13d) [61, 62]. 

The quality of the Si/Si02 interface is crucial in MOS devices. The interfacial structure or the flatness on the atomic scale becomes very important as the demands for very thin oxide increases. The Si/Si02 interfacial structure has been studied by TEM, and by AFM/STM for the surfaces after the oxide layer is removed by chemical etching. Here, we report a novel electrochemical method for the evaluation of the interfacial structure, which can be applicable to a wide range of the thickness of the oxide layers. 

Semi-concentrated emulsions were examined theoretically and experimentally only within the linear viscoelastic region [Oosterbroek and Mel-lema, 1981 Oosterbroek et al., 1980, 1981 Eshuis and Mellema, 1984], Recognizing that the interphase has a final thickness (sometimes the total volume of interphase is comparable to, or even exceeds, the volume of the dispersed phase) the authors postulated that the interphase should have two interfacial coefficients, v and v facing the two principal polymer domains. Next, two models of the interphase were evaluated (i) a two-dimensional viscoelastic film, and (ii) the interphase of final thickness. Both led to at least two relaxation times ... 

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