Masters Theses

Date of Award

12-2002

Degree Type

Thesis

Degree Name

Master of Science

Major

Chemistry

Major Professor

Linda J. Lee Magid

Abstract

Polyionenes are strongly charged cationic polyelectrolytes whose charged groups are located on the polymer main chain. During the last few decades, interest in them has increased because of their similarity to DNA, protein and other biological related structures. The charge density of the polyionenes can be changed by changing the number of methylene groups, [x,y], between the quatemized nitrogen atoms. In our systems, we synthesized [3,3], [6,6], and [8,8] polyionenes to produce different charge density parameters, ξ; and we chose chloride and 2,6-diclorobenzoate as counterions in order to investigate the counterion effect on the conformation of the polyionenes. By changing the polyionene charge density, polyionene concentration, counterions, or ionic strength in the solutions, the conformation of the polyionenes can be changed. Small-angle neutron scattering (SANS) was used to study the conformation of polyionenes in aqueous solutions. From the scattering curves, we obtained information on the chain conformation and interchain interactions. We also tried to fit the scattering curves for solution of higher ionic strength by using the Debye coil scattering funcfion, and we observed that using only the form factor to fit the scattering was unsuccessful. Further attempt was also made to fit the scattering curves using the random phase approximation, and decreases in the excluded volume parameter were observed as the ionic strength increased.

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