Title: The study of polyelectrolyte systems near solid surfaces using the method of Monte-Carlo
Author: Kika_san
Company: home

Antjuhova Marjana

Annotation of  the Master dissertation

The study of polyelectrolyte systems near solid surfaces using the method  of Monte-Carlo 

In this work lattice (on a simple cubic lattice) polymer models  were considered, calculation of which thermodynamic parameters were realized method of Monte-Carlo with the help of the algorithm of Wanga — Landau. This method has shown good results which will be coordinated with the exact data, theoretical dependences and experimental data.
Interaction of single polymer with the infinite homogeneous "wall" occupying semispace with an infinite flat side was investigated. The program modeling an athermic case, without power interaction of polymer and "wall" is realized. Superfluous entropy of polymer in comparison with a phantom chain of the same length depending on distance from polymer to surface is defined.
For a thermal case the program sorting system on number of contacts a monomer — a monomer and to number of contacts a monomer — "wall" is realized, and to each type of contacts have been compared various energy. The distribution functions of systems on energy are as a result defined, using which, average energy, heat, root-mean-square distance between the polymer ends, average distance (heights) from polymer to a surface as temperature functions are calculated.
The temperature fall there is considered as a reduction of the sizes of polymer and its sedimentation by "a wall" surface. At a variation of parameters of model these processes can occur or synchronously, or reduction of the sizes precedes sedimentation, or, on the contrary, polymer  compactization occurs after sedimentation on "wall". In the latter case sedimentation of a friable ball is accompanied by increase in its sizes, компактизация occurs only at the further reduction of temperature.
Interaction of a single polyion with the infinite charged homogeneous "wall" occupying semispace with an infinite flat side, at presence counterions was investigated. The case when the polyion and "wall" have odes-noimyonnye charges was considered. At system were present counterions which number stole up such that the electroneutrality was observed. Between system elements it was entered кулоновское interaction. The program for calculation of thermodynamic dependences of system is realized.  Temperature dependences of a specific thermal capacity, root-mean-square races-standings between the ends of a polyion, average distance of the center of weights of a polyion from "wall" and average z-coordinate of ions.
The effect of upsetting of the polyion on the same charged substrate is detected At temperature fall approach (upsetting) a polyion to "a wall" surface is observed. The effect amplifies at increase in a charge of ions. It gives the chance to assume that for the mechanism description of the upsetting it is enough to use electrostatic interaction.