The Polyelectrolyte Brush: Poor Solvent

1991 ◽  
Vol 248 ◽  
Author(s):  
Richard S. Ross ◽  
Phil Pincus

AbstractWe investigate the end grafted polyelectrolyte brush in the poor solvent regime of the corresponding neutral polymer system. Using Poisson-Boltzmann theory for the electrostatics and Flory-Huggins-mean-field theory for the excluded volume and Van-der-Waals-like monomer interactions, we find the existence of a first order phase transition to a collapsed state for moderate to highly charged polyelectrolytes in the poor solvent regime. Irreversibilities in the disjoining pressure between planar grafted surfaces are predicted. For polyelectrolytes grafted to spherical and cylindrical surfaces with small radii of curvature, the phase transition is predicted to become second order in the infinite molecular weight limit. A phase diagram for the entire poor solvent regime is given.

1995 ◽  
Vol 09 (21) ◽  
pp. 1347-1351 ◽  
Author(s):  
HASAN M. AL MUKADAM ◽  
DIMO I. UZUNOV

The mean field theory is used for the analysis of a two-sublattice system of Ising spins, which describes ferro-, antiferro-, and ferrimagnetic orderings. It is proven that the phase transition in these systems is of a first order when the exchange constants of the sublattices are different. The free energy, the order parameter profiles and the latent heat of the phase transition are calculated for almost equivalent sublattices.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
A. Pustogow ◽  
R. Rösslhuber ◽  
Y. Tan ◽  
E. Uykur ◽  
A. Böhme ◽  
...  

AbstractCoulomb repulsion among conduction electrons in solids hinders their motion and leads to a rise in resistivity. A regime of electronic phase separation is expected at the first-order phase transition between a correlated metal and a paramagnetic Mott insulator, but remains unexplored experimentally as well as theoretically nearby T = 0. We approach this issue by assessing the complex permittivity via dielectric spectroscopy, which provides vivid mapping of the Mott transition and deep insight into its microscopic nature. Our experiments utilizing both physical pressure and chemical substitution consistently reveal a strong enhancement of the quasi-static dielectric constant ε1 when correlations are tuned through the critical value. All experimental trends are captured by dynamical mean-field theory of the single-band Hubbard model supplemented by percolation theory. Our findings suggest a similar ’dielectric catastrophe’ in many other correlated materials and explain previous observations that were assigned to multiferroicity or ferroelectricity.


2005 ◽  
Vol 19 (18) ◽  
pp. 2975-2987 ◽  
Author(s):  
ARIF NESRULLAJEV ◽  
FATMA Z. TEPEHAN

In this work, the effect of thin films on the orientational, thermotropic and optical properties and on the peculiarities of the nematic–isotropic liquid phase transition has been carried out. The planar textures of MBBA+EBBA eutectic mixture on the surfaces coated with Al 2 O 3 and ZrO 2 thin films have been obtained. The optical and thermodynamical parameters of the obtained, oriented textures have been determined. The effect of thin films on the temperature width of heterophase region and on the nematic–isotropic liquid phase transition temperatures has been investigated. The shift of the phase transition temperatures and the change of the temperature width of the heterophase region have been revealed. For the analysis of peculiarities of the nematic–isotropic liquid phase transition and the heterophase regions of this transition, the mean field theory has been used.


Author(s):  
Thies Jansen ◽  
Alexander Brinkman

Abstract Electron-electron interactions can be useful for realizing new nontrivial topological phases of matter. Here, we show by means of a tight-binding model and mean field theory how electron-electron interactions can lead to a topological phase transition. By externally adding or removing electrons from the system a band inversion between two bands with dierent parity is induced. This leads to a topological nontrivial phase if spin-orbit coupling is present. Besides the toy-model illustrating this mechanism, we also propose SmB6 as a possible playground for experimentally realizing a topological phase transition by external tuning.


2002 ◽  
Vol 11 (04) ◽  
pp. 545-559 ◽  
Author(s):  
V. K. GUPTA ◽  
ASHA GUPTA ◽  
S. SINGH ◽  
J. D. ANAND

We have studied phase transition from hadron matter to quark matter in the presence of high magnetic fields incorporating the trapped electron neutrinos at finite temperatures. We have used the density dependent quark mass (DDQM) model for the quark phase while the hadron phase is treated in the frame-work of relativistic mean field theory. It is seen that the energy density in the hadron phase at phase transition decreases with both magnetic field and temperature.


2016 ◽  
Vol 18 (6) ◽  
pp. 4394-4404 ◽  
Author(s):  
D. O. López ◽  
B. Robles-Hernández ◽  
J. Salud ◽  
M. R. de la Fuente ◽  
N. Sebastián ◽  
...  

We have developed a Landau model that predicts a first order twist-bend nematic–nematic phase transition.


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