Assembly of Ionizable Triblock co-Polymer in THF Solutions

Recent efforts to design high energy density light weight capacitors brought to the forefront triblock copolymers that contain ionizable segments. These triblocks of the form ABC, where the end block is highly ionizable, preferably in the polyelectrolyte regime, forms domains that are highly polarizable.  The other two blocks provide a structured matrix that separates these ionic domains and provide mechanical stability. Transforming this idea to an actual device requires control over assembly of a complex polymer in the high segregation limit. Here using atomistic molecular dynamics simulations, we follow the assembly of a model triblock co-polymer with tert-butyl polystyrene-b-polyethylene-r-propylene-b-sulfonated polystyrene with sulfonation levels varying from 0 to 95% in dilute solutions THF.  THF is a polar solvent that experimentally dissolves the triblock.  We find that across all sulfonation levels, the ionizable blocks as well as the t-butyl styrene blocks assume an extended conformation. The rubbery segment however fold to form a nano domain with enhanced order.  The talk will further expound on the correlation between the sulfonation levels and the structure dynamics of each of the components in solutions.