Particle-Based or Field-Based Models for Polymer Systems?

Daming Li

doi:10.4172/2168-9679.1000e104

Abstract

Compared to the systems which are composed of simple atomsor molecules, the structures of polymer systems in equilibrium are richer. The main reason is that a polymer molecule is composed of many monomers with the same or different chemical property. Take AB diblock copolymers as an example. Each molecule has a form AA•• •ABB• ••B where the monomer A and B have different chemical properties. The equilibrium structures for diblock copolymer, e.g.,lamellar, hexagonal cylinder, bicontinuous gyroid and bcc sphere, etc, have been found for different composition of monomer B through computation [1] and experiments [2]. This equilibrium structures(A-rich and B-rich phase domain) with a length scale of 10-100 nm, is the result of competition of two factors: the repulsion of two chemically distinct monomer A and B, and the conformal entropy penalty. Since monomers A and B are connected in each molecule, monomer A and B are only be separated microscopically. Thus it is called microseparation.

Highlights

Compared to the systems which are composed of simple atoms or molecules, the structures of polymer systems in equilibrium are richer
E.g., monomer density, pressure, etc, can be calculated if we know the partition function which is based on the interaction between monomers
Each polymer molecule can be regarded as a continuous curve, the partition function is the summation of action over all these paths, but it is still a particle-based description! The field-based models use the fact that this particle-based partition function can be written as the functional integral over density and auxiliary field using Hubbard-Stratonovich transformation

Summary

Introduction

Compared to the systems which are composed of simple atoms or molecules, the structures of polymer systems in equilibrium are richer. Particle-Based or Field-Based Models for Polymer Systems? The particle based models include the molecule dynamics, Monte Carlo methods, Brownian dynamics [3].

Results

Conclusion