Interrelation of Hierarchy of Structures at Comparison of Linear and Cross-linked Polymer Compounds

Ibragim Suleimenov,Galym Mamytbekov,Esen Bekturov

doi:10.18321/ectj567

Abstract

The comparison of behavior of a linear polymer compounds and cross-linked networks are carried out. It is shown, that the correspondence between rheological behavior of a linear polymer compound and macroscopic behavior of its cross-linked analog is determined by topology of structures describing a hydrogel as qualitatively new object as well as by the type of polymer – solvent interactions. In this situation swelling degree is completely described by the Katchalsky – Lifson’s theory. Moreover it is possible to predict microscopic behavior of macromolecular chains on the base of experimental studies of macroscopic specimens of the gel. Such investigations may be carried out in direct way for organogels. When the gel is charged (polyelectrolyte effect takes place) it is necessary to make some correction. The fact is due to so called effect of concentration redistribution, which occurs when surface of the gel acts as a membrane. In such situation the concentration of low-molecular salt inside gel may be quite more low then the concentration of the salt outside specimen. Thus in the solutions of ionogenic salts real behavior of the specimen is determined not average concentration of salt, but the real concentration of salt inside of the gel. Measuring this concentration experimentally it is possible to carried out investigations of charged macromolecular chains on the base of macroscopic specimens too.

Highlights

At present a number of different theories describing the swelling of polymer gel are known well
It is necessary to describe the free energy of electrostatic energy in details taking into account real configuration of macromolecular coil
It was shown that the dependence of swelling ratio Ks of polymer gel on chemical composition of the surrounding media is similar to the dependence of reduced viscosity [η] of linear polymer on the same parameter (Fig. 2)

Summary

Introduction

At present a number of different theories describing the swelling of polymer gel are known well. Katchalsky and Lifson’s theory describes polymer gel as a collection of macromolecular chains [1]. The opposite limit case is the subject of diffusional theory [3] which describes strongly charged polyelectrolyte networks. The main difference between mentioned limit cases is likely to be determined by topology of gel structures.

Results

Conclusion