Solid-state morphologies of linear and bottlebrush-shaped polystyrene–poly(Z-l-lysine) block copolymers

The solid-state structures of polystyrene–poly(Z-l-lysine) block copolymers were examined with respect to the polymer architecture and the secondary structure of the polypeptide using circular dichroism, quantitative small- and wide-angle X-ray scattering, and electron microscopy. Linear block copolymers exhibit a hexagonal-in-lamellar structure where folded and packed polypeptide α-helices form lamellae which extend over an exceptional broad range of the composition diagram. Star- or bottlebrush-shaped copolymers are able to stabilize a larger interface area than linear ones which promotes the formation of undulated lamellar mesophases. Depending on the secondary structure of polypeptide segments, plane lamellar, superundulated lamellar, or corrugated lamellar phases are formed. These results indicate the importance of a secondary structure and packing of polymer chains for the formation of new phases and ordering far from the ‘classical’ phase behavior.