Effect of zwitterion substitution on the structure and dynamics of asymmetrically substituted polystyrene-block-polyisoprene diblock and triblock copolymers

We have studied the effect of zwitterion (Zw) substitution on asymmetrically functionalized copolymers of the type ZwIS, ZwSI (where I is polyisoprene and S is polystyrene), and of diblock and triblock copolymers functionalized at both ends (ZwISZw) and junctions (SZwIZwS), respectively. We have employed SAXS, rheology and dielectric spectroscopy to study the structure and dynamics. The positioning of the short but strongly incompatible polar group with respect to the S and I blocks strongly affects the structure and dynamics of the material because of aggregation. The aggregation strongly modifies the electron density profiles, which reflects in the alteration of the SAXS spectra. The most pronounced effects are found when the functional group is located within the center of the domain with the lowest electron density (polyisoprene).