Charge Interaction of Synthetic Polycarboxybetaines in Bulk and Solution

Abstract

Various polycarboxybetaines were synthesized using controlled radical polymerization processes followed by polymer analogous transformations. Structural variation of these exclusively aromatic or heteroaromatic systems includes distance between charges, hybridization and substitution of the ammonium moiety, and additional alkyl chains between the charges. For the first time capillary electrophoresis was used for systematic characterization of the solution properties. It was found to be a very sensitive method to detect even small structural differences and the resulting pH-dependent solution behavior. The electrophoretical mobility compared with an internal standard and the amount of its pH dependence are direct measures for the interaction of charges of polycarboxybetaines in solution. This method clearly reveals a gradual and more or less predictable content of “free” cationic charges dependent on structural and solution parameters. Results obtained coincide in a fairly good way with data from FTIR measurement and charge titration.