(24e) Thermodynamics of Salt-Doped Polymers

There is much current interest in salt-doped polymers as materials for energy applications.  For example, a promising system for rechargeable battery applications consists of diblock copolymers of an ion-dissolving block, typically polyethylene oxide (PEO) and a nonconducting block such as polystyrene.   The addition of lithium salts has been shown to significantly alter the order-order and order-disorder transition temperatures, reflecting a change in the effective miscibility between the two polymer blocks.  In this talk, I will present a theory for explaining and predicting the change in polymer miscibility due to the addition of salt ions.  Our results show that the preferential solvation energy of the ions by the polymers plays a key role in the thermodynamics of these salt-doped polymer systems.  The change in the domain spacing in the ordered block copolymers phases with salt concentration and the distribution of ions in the block domains will also be discussed.