Phase Separation by Spinodal Decomposition in Isotropic Systems

1965 ◽  
Vol 42 (1) ◽  
pp. 93-99 ◽  
Author(s):  
John W. Cahn
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

scholarly journals A computational study of phase separation in polymer solutions under a double quench

2021 ◽  
Author(s):  
Ehsan Hosseini
Keyword(s):  
Phase Separation ◽  
Polymer Solution ◽  
Spinodal Decomposition ◽  
Computational Study ◽  
Stable State ◽  
Thermal Quenching ◽  
Nucleation And Growth ◽  
Two Dimensions ◽  
Numerical Work ◽  
Binary Polymer

Polymer-dispersed liquid crystals (PDLCs) are a relatively new class of materials used for many applications ranging from switchable windows to projection displays. PDLSs are formed by spinodal decomposition induced by thermal quenching or polymerization. The objective of the present study is to introduce a new mechanism of phase separation in a binary polymer solution and develop a mathematical model and computer simulation to describe the phase separation during the early and intermediate stages of nucleation and growth and spinodal decomposition induced by thermal double quenching. The growth equilibrium limits of phase separation as well as phase transition are calculated by taking into consideration the Flory-Huggins theory for the free energy of mixing. A two step quench is modeled using Cahn-Hilliard theory for asymmetric binary polymer solution which is quenched from a stable state in the one-phase region to a metastable region where nucleation and growth occurs. The solution is allowed to coarsen for different time periods before a second quench was applied to a point further inside the phase diagram. The numerical results in two dimensions replicate the experimental and numerical work that has been recently done and published.

On Domain Structure and Local Curvature in Lipid Bilayers and Biological Membranes

1977 ◽  
Vol 32 (7-8) ◽  
pp. 581-596 ◽  
Author(s):  
C. Gebhardt ◽  
H. Gruler ◽  
E. Sackmann
Keyword(s):  
Electron Microscopy ◽  
Phase Separation ◽  
Domain Structure ◽  
Spinodal Decomposition ◽  
Defect Structure ◽  
Experimental Result ◽  
Domain Pattern ◽  
Local Curvature ◽  
Lipid Organization ◽  
Ripple Phase

Abstract The lateral lipid organization and the local surface curvature in small and giant bilayer vesicles of binary lipid mixtures were investigated. Mixtures of the following lipids are studied: Cholesterin, di-alcyl-lecithins, dioleyl-lecithin and di-alcyl-phosphatidic acid. The latter is considered as being representative of charged natural lipids (e.g. phosphatidyl serine or cardiolipin). Three different experimental methods are compared: 1) The excimerfluorescence method, 2) the spin label technique and 3) the freeze fracture electron microscopy. The latter two methods yield information on the size of lipid precipitations. The surface curvature may be studied by electron microscopy. The essential experimental results are: (1) Mixtures of smectic phases of different symmetry undergo lateral phase separation. (2) The phase separation leads to a domain-like lateral lipid organization. (3) The domain structure is often accompanied by a variation in local curvature. (4) In membranes containing a charged lipid component, the domain structure may also be triggered by external charges (such as surface proteins). (5) two types of domains are observed: Circular domains (diameters of the order of several 100 Å) occur in mixtures of non-tilted fluid and rigid phases. Elongated domains (width ∼ 100 Å) are observed in mixtures of tilted and nontilted phases. This domain pattern is characteristic for mixtures of lecithins and cholesterols. The domain structure is explained by combining the theory of spinodal decomposition of alloys with the essential result of the orientational elastic model of membranes. The domain size calculated from this model agrees well with the experimental result. The periodic ripple structure observed between the pre-and the main transition is explained by generalizing the concept of spinodal decomposition to include the separation of phases which are only distinguishable (e. g. by the tilt angle). The width of the domains in equilibrium is explained in terms of the spontaneous curvature of the decoupled monolayer of a bilayer. Good agreement with the experimental result is obtained. The ripple phase is only a special case of the surface induced domain structures in ordinary liquid crystals. The defect structure of the ripple phase has been analysed in terms of its symmetry. A symmetry rule is established which leads to a model of lipid orientation. Below the pretransition no periodic domain pattern is observed under normal conditions. But upon cooling a bilayer very rapidly a defect structure reminiscent of a screw dislocation is ob­ served. This is expected for coupled biaxial monolayers.

MODIFIED ANYON (MANYON) THEORY OF HETEROGENEOUS ELECTRONIC PHASES

1990 ◽  
Vol 04 (09) ◽  
pp. 1551-1565 ◽  
Author(s):  
R.S. MARKIEWICZ
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Potential Interest

There is a purely electronic analog to spinodal decomposition in alloys. A number of examples of such phase separation are presented, including one of potential interest to high-Tc superconductivity. It is speculated that, under some circumstances, the heterogeneous state may be described by a modification of the anyon theory.

Kinetics of phase separation by spinodal decomposition in mixtures of telechelic hydroxy-terminated polyisobutylene and poly(tetrahydrofuran)

1991 ◽  
Vol 24 (17) ◽  
pp. 4852-4856 ◽  
Author(s):  
Hak Soo Lee ◽  
Thein Kyu ◽  
Avi Gadkari ◽  
Joseph P. Kennedy
Keyword(s):  
Phase Separation ◽  
Spinodal Decomposition ◽  
Kinetics Of

Kinetics of phase separation at the early stage of spinodal decomposition in epoxy resin modified with PEI blends

2008 ◽  
Vol 287 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Wenjun Gan ◽  
Yingfeng Yu ◽  
Xiaoyun Liu ◽  
Minghai Wang ◽  
Shanjun Li
Keyword(s):  
Phase Separation ◽  
Epoxy Resin ◽  
Spinodal Decomposition ◽  
Early Stage ◽  
Kinetics Of
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