Title

Synthesis and Solution Behavior of Electrolyte-Responsive Polyampholytes

Date of Award

1991

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Polymers and High Performance Materials

First Advisor

Charles L. McCormick

Advisor Department

Polymers and High Performance Materials

Abstract

Electrolyte responsive water soluble polyelectrolytes and polyampholytes have been studied to establish fundamental structure/property relationships for these classes of polymers. Copolymers of acrylamide (AM) with sodium 3-acrylamido-3-methylbutanoate (NaAMB), 2-methyl-2-acryl-amidopropanetrimethylammonium chloride (AMPTAC) and 3-(2-acrylamido-2-methylpropanedimethylammonio)-1-propanesulfonate (AMPDAPS), and terpolymers of AM with AMPTAC and NaAMB or sodium 2-acrylamido-2-methylpropanesulfonate (NaAMPS) were synthesized and characterized. The presence of added electrolytes in the copolymerization of AM with NaAMB facilitated charged monomer incorporation and produced copolymers with microstructures different from those obtained in copolymers synthesized in deionized water. Electrolytes were further used in the polymerization reactions of polyampholytes in order to maintain homogeneity and allow random incorporation of the ionic monomers. The new cationic monomer AMPTAC was synthesized as a quarternized analog of 2-arcylamido-2-methylpropanedimethylammonium hydrochloride (AMPDAC). Copolymerization of AMPTAC with AM in various feed ratios yielded a series of copolymers which were stable to changes in pH and maintained fixed charge densities regardless of microenvironment. Copolymers of NaAMPS with AMPTAC possessed polyelectrolyte or polyampholyte characteristics dependent on the concentration of AMPTAC in the copolymers. In aqueous solutions, the copolymers with charge imbalances behaved as polyelectrolytes while those with equal or near equal molar charge concentrations behaved as polyampholytes. Terpolymers of AM with NaAMPS and AMPTAC were synthesized with random distributions of the charged mers along the chains. Solution behavior was complex due to the existence of intra- and intermolecular interactions. Soluble terpolymers of AM with NaAMB and AMPTAC were synthesized with random distributions of the charged mers and compositions which reflected the feed. These polymers could be transformed into polyelectrolytes by decreasing the solution pH below the pKa of the NaAMB mer. Ampholytic copolymers with varying ratios of AM and the zwitterionic monomer AMPDAPS were synthesized and characterized. Copolymers containing greater than 40 mol % AMPDAPS were insoluble in deionized water but readily dissolved in the presence of NaCl.