Molecular segregation

Molecular Segregation at Periodic Metal Nano-Architectures on a Solid Surface... 

The disordered arrangement of the globuh and worm-hke species in combination with their uniform shape and diameter of 50 A demonstrates that the intramolecular self-assembly did not depend on intermolecular ordering. For both types of particles, the monolayer thickness was similar to the lateral diameter of the particles d = 50 5A. The topographic contrast of the images in Fig. 6 was enabled by strong molecular segregation and weak interpenetration of the particles. 

Carrera, C. and Patino, J.M.R. Flow-induced molecular segregation in p-casein-monoglyceride mixed films spread at the air-water interface, Langmuir, 20, 6327, 2004b. 

Looking at the number and the position of the alkoxy substituents, a relationship between the molecular structure and the mesomorphic properties can be emphasised. While substituents at the para position seem fairly important to promote mesomorphism, the columnar behaviour is clearly connected to substitution at the meta position. Substitution at the ortho position seemed to disfavour the induction of calamitic mesomorphism, as the lateral interactions and the molecular segregation are reduced, but does not disfavour columnar mesophases, providing that the space is properly filled by aliphatic substituents. 

In addition, biological membranes are believed to be composed of an inhomogeneous distribution of molecular assemblies, such as specific ionic channels, and molecular segregation with respect to the two-dimensional surfaces of the membranes occurs, which is quite a different situation from that in simple phospholipid membranes. 

Dixit, S., J. Crain, W. C. K. Poon, J. L. Finney, and A. K. Soper, Molecular segregation observed in a concentrated alcohol-water solution. Nature, 2002.416 829-832. 

Addison A, Ribeiro M, Deffieux A, Fontanille M (1992) Polymer 33(20) 4337 Miiller AJ, Hernandez ZH, Amal ML, Sanchez JJ (1997) Successive self-nucleation/ aimealing (SSA) a novel technique to study molecular segregation during crystallization. Polym Bull 39 465 72... 

If one assumes that a fully developed N phase (the degree of liquid crystallinity is unity) is formed on cooling, a process which is facilitated by the large drop in viscosity at the I-N transition, the smaller value of Ah, may be attributed to an incomplete isotropization on heating. Perhaps, as a direct result of molecular segregation across the biphase. 

Cheng SZD, Noid DW, Wunderlich B (1989) Molecular Segregation and Nucleation of Poly(elhylaie oxide) Crystallized from the Melt. IV. Computer Modeling. J Polymer Sd Part B Polymer Phys 27 1149-1160. 

Hu WB (2005) Molecular segregation in polymer melt crystallization simulation evidence and unified-scheme interpretation. Macromolecules 38 8712-8718 Hu WB, Cai T (2008) Regime transitions of polymer crystal growth rates molecular simulations and interpretation beyond Lauritzen-Hoffman model. Macromolecules 41 2049-2061 Jeziomy A (1971) Parameters characterizing the kinetics of the non-isothermal crystallization of poly(ethylene terephthalate) determined by DSC. Polymer 12 150-158 Johnson WA, Mehl RT (1939) Reaction kinetics in processes of nucleation and growth. Trans Am Inst Min Pet Eng 135 416-441... 

Abstract. We review how the nucleation mechanism of polymer crystallization could be assigned to intramolecular processes and what are the preliminary benefits for understanding some fundamental crystallization behaviors. The speculative concept of molecular nucleation and the theoretical model of intramolecular nucleation have been elucidated in a broad context of classical nucleation theory. The focus is on explaining the phenomenon of molecular segregation caused by polymer crystal growth. 

Similar formulae in terms of the Fresnel reflectances may be built up for the situation with a small number of discrete layers. A larger number of layers demands the use of a more general method in which the surface is considered in terms of a series of layers of slightly diflerent characteristics. The models that are used in practice consider the density variation to be a smooth function of the distance from the surface but also may include specifically a diflerent surface layer to account for surface roughness and the possibility of molecular segregation at the surface. 

Besides molecular segregation (Hu 2005), many other phenomena unique for polymer crystal growth also favor the intramolecular nucleatimi model, such as co-crystallization of long and short chains (Cai et al. 2008 Jiang et al. 2015) as well as the interpretation of regime transitions (Hu and Cai 2(X)8). 

Cheng SZ, Wunderlich B (1986) Molecular segregation and nucleation of poly (ethylene oxide) crystallized from the melt. I. Calorimetric study. J Polym Sci B 24(3) 577-594 Coleman BD (1958) On the properties of polymers with random stereo-sequences. J Polym Sci 31 (122) 155-164... 

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