Luminescence probe studies of ion-containing polymers

Abstract

Luminescence probe studies were used to obtain information about the morphology and chemical properties of ion-containing polymers (ionomers). Studies were conducted in polyelectrolyte solutions and solid state ionomer membranes. The data obtained was compared to similar data from homogeneous solvents and micellar solutions. The response of the luminescence probes were similar in the ionomer membranes and their corresponding solutions. A concerted hydrophobic/electrostatic interaction was implied in the binding of the probe ions to the polyanions in solution. This concerted binding provided an effect which could undoubtedly be exploited in a luminescence titration method. The basis for the determination of the equivalent weight or the concentration of a poly-electrolyte solution using this method was explored. Further evidence for the importance of hydrophobic interactions in ionomeric systems is presented. The effects of ionic sites clustering in ionomer membranes were studied. The results suggested the ionic clusters have frequent local instrusions of the chain material phase and are dynamic with respect to water content and counterion. A relatively small fraction of the ionic sites were found to be incorporated in a very hydrophobic domain. The particular operative interactions between the probes and the ionomers were found to be dependent on the nature of the polymer chain material. The significance of these results is discussed.