Polyelectrolyte Multilayers and Complexes: Glass Transitions and Dynamics

Polyelectrolyte multilayers and complexes, both made from the assembly of oppositely charged polymers, bear many similarities. This talk will compare the glass transition behavior of multilayers and complexes that contain strong and weak polyelectrolytes, different salt types and concentrations, and different amounts of water. The experimental glass transition decreases with increasing salt and/or water content, which is well-described by the ratio of the number of intrinsic pairs to water molecules. Similarly, the dynamic mechanical behavior and the associated relaxation time are also well-described by the ratio of the number of intrinsic pairs to water molecules. To understand this behavior for individual polyelectrolyte chains within the complex, the polyelectrolyte’s diffusion coefficient is estimated using fluorescence recovery after photobleaching (FRAP) and correlated to the salt concentration of assembly. Taken together, these results indicate the importance of water’s role in lubricating or modifying the strength of the intrinsic ion pair for a larger scale relaxation of the multilayer or complex.