Intermediate segregation limit

In the opposite limit of strong segregation (SSL) x 2, the free energy can also be expressed in terms of a square gradient functional, and one obtains qcR = 6 xN - 2). At intermediate segregation, which is most relevant to experiments, the square-gradient approximation breaks down and there is... 

In many applications, including colloid stabilization, polymers are end-grafted onto large particles which are intermediate between the planar brush and a star. Curved brushes, with either spherical or cyUndrical symmetry, can also be formed by asymmetric diblock copolymers in the strong segregation limit. When the grafting surface curves towards the polymers (concave curvature), the volume available to the polymer chains is lowered compared to a flat surface. In this case, the chains are stretched throughout the brush and the brush is qualitatively unaltered from the flat case. MC simulations on a tetrahedral lattice for chains inside a spherical cavity... 

The system of H chemisorbed on Cu/Ni is examined both with and without surface segregation. In the case of cs = Cb (i.e., no surface segregation), the curve of AE vs q, is shown in Fig. 6.3(a), and is seen to have a monotonic behaviour, which is almost linear for intermediate values of c, . In the dilute limits (cfe close to 0 or 1), AE is closer to the value for the corresponding pure system than a purely linear relationship would produce, which suggests that the effect of any minority atoms, even near the surface, is cancelled by the averaging process used in the CPA. 

The limitation of the ex situ approach is that the composition and structure of the catalyst surface are not investigated under reaction conditions. This limitation prevents the post-mortem analysis of the catalyst under UHV to determine an assessment of the surface restructuring, intermediate species, segregation of specific components, etc., that are characteristic of reaction conditions. 

Cho et al. (2000) studied the segregation dynamics of block copolymers to the interface of an immiscible polymer blend and compared experimental results to the predictions of various theories for a poly(styrene-b-dimethylsiloxane) [P(S-b-DMS) M = 13,000] symmetric diblock copolymer system added to a molten blend of the corresponding immiscible homopolymers. They used the pendant drop technique at intermediate times and compared their results to the predictions of diffusion-limited segregation models proposed by Budkowski, Losch, and Klein (BLK) and by Semenov that have been modified to treat interfacial tension data. The apparent block copolymer diffusion coefficients obtained from the two analyses fall in the range of 10 -10 cm /s, in agreement with the estimated self-diffusion coefficient of the PDMS homopolymer matrix. 

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