Interfacial structures of triblock copolymers and their chain conformations in bulk

Abstract Surface characteristics of a 2-vinylpyridine–styrene–2-vinylpyridine (PSP) two-component triblock copolymer and an isoprene–styrene–2-vinylpyridine (ISP) three-component triblock copolymer, whose volume fractions of their center block polystyrene, φ s , were both 0.5, were compared in connection with their chain conformations. The former exhibited alternating lamellar structure, while the latter revealed periodic tricontinuous structure. Chain dimension of S block of PSP was measured by small angle neutron scattering (SANS) and it has been found that polystyrene chain is elongated toward the direction normal to lamellar interface but the degree of deformation is less than that of SP diblock copolymer. Interfacial thickness of PSP, actually 2-vinylpyridine–styrene-d 8 –2-vinylpyridine) (PDP) triblock copolymer was measured by neutron reflectivity and estimated to be 4.5 nm, which is essentially the same as that for SP diblock copolymer interface. Alternatively, the features of tricontinuous structure of ISP were determined to have characteristics of parallel surfaces to G-surface, which is one of the infinite minimal surfaces, by transmission electron microscopy and small angle X-ray scattering.