Interfacial segregation

Graciaa A, Lachaise J, Cucuphat C, Bourrel M, Salager JL (1993) Interfacial segregation of ethyl oleate/hexadecane oil mixture in microemulsion systems. Langmuir 9 1473-1478... 

The comparison of the surface structures on two substrates suggests strong surface effects on the microphase separation. For lamella systems, the degree of interfacial segregation has been shown to be proportional to the surface potential [146], The same line of argument can be used to explain the surface field effects... 

The compositional profiles of C, O, and Si in polycrystalline silicon were reported by Pizzlni et al. [167], who used the secondary ion mass spectrometry (SIMS) to determine the interfacial segregations. The segregation enthalpies and entropies for C and O in polycrystalline silicon have been estimated and listed in Table 13.1. The calculated C and O segregations (solid lines) are compared with the measured values and shown in Fig. 13.28. 

Fig. 43.a Composition-depth profiles [251, 254] of PI(NA=114)-dPS diblock copolymers with various N-mer brush forming dPS blocks (N=89 (0),893 (A), and 9551 ( )) at the free surface of the high molecular weight P-mer (P>2.9 N) PS host matrix, b The corresponding segregation isotherms analyzed with mean field (solid lines, Eq. (67b) and self consistent mean field (SCMF, dashed lines) approaches, c Normalized interfacial segregation of dPS blocks z N/Rg(N) as a function of the normalized chemical potential of Eq. 68 [254]. The solid line shows the SCMF master curve [237]... 

Other models for the segregation coefficient have been developed specifically for the case of solution crystal growth and with less restrictive assumptions that allow for nonidealities in both the liquid and solid phases. For such a development, the interfacial segregation coefficient is redefined in the following manner... 

Such situations of interfacial segregation are not typical of pH-dependent systems, but rather they are inherent to mixtures that contain amphiphilic species with very different hydrophilic-lipophilic tendencies [75,86]. 

Mansky P, Russell TP, Hawker CJ, Mays J, Cook DC, Satija SK (1997) Interfacial segregation in disordered block copolymers Effect of tuneable surface potential. Phys Rev Lett 79(2) 237-240... 

This chapter also discusses those factors that play a key role on the segregation process that can be classified as entropic and enthalpic factors. Whereas entropic factors include those related with the macromolecular structure (molecular weight or degree of branching), enthalpic factors involve the chemical functionality of the components in the polymer blend. In addition, the environment of exposure can dramatically modify the segregation depending on the polarity. Exposure of a polymer surface to a moist atmosphere resulted in an interfacial enrichment in the polar component. On the contrary, vacuum or dry environments favor the interfacial segregation of the less polar additive. 

Kawaguchi, D., Tanaka, K., Torikai, N., Takahara, A., Kajiyama, T. Surface and interfacial segregation in blends of polystyrene with functional end groups and deuterated polystyrene. Langmuir 23, 7269-7275 (2007)... 

A modified solute drag model, taking into account the interfacial segregation of alloy elements, is applied to the decomposition of austenite into ferrite in the C-Fe-Mo alloys [1997Liu]. The ealeulations are performed with assessed thermodynamic and kinetic data stored in a database. The solute drag-like effeet suggested in the literature is discussed in comparison with the quantitative calculation by [1997Liu]. 

C. A. Jalbert, Ph.D. Dissertation, Surface and Interfacial Segregation in End Functionalized Polymers, University of Connecticut, 1993. 

To account for the large aitiount of retained impurities the interfacial segregation coefficient must be increased and in a comparison of experimental depth profile with a model calculation it can be used as a fitting parameter. 

Mansky, P., Russell, T.P. etoL (1997b) Interfacial segregation in disordered block copolymers effect of tunable surface potentials. Physics Review Letters, 79(2), 237 240. 

One consequence of interfacial segregation based on polarity is strongly nonuniform orientational distributions of amphiphiles. For example, the vector directed from the nonpolar to the polar end of the solute (e.g., from the methyl carbon to the hydroxyl oxygen atoms in alcohols) clearly points toward water. The distribution of this vector, calculated from computer simulations, peaks at the orientation perpendicular to the interface and rapidly decreases as the vector becomes parallel. The probability of finding the vector pointing towards the nonpolar phase is negligible. From equation (8) it follows that a considerable free energy is required to invert the orientation of an amphiphile at the interface. 

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