Interfacial structures of triblock copolymers and their chain conformations in bulk

Surface characteristics of a 2-vinylpyridine-styrene-2-vinylpyridine (PSP) two-component triblock copolymer and an isoprene-styrene-2-vinylpyridine (T SP) three-component triblock copolymer, whose volume fractions of their cen ter block polystyrene, phi(s), were both 0.5, were compared in connection w ith their chain conformations. The former exhibited alternating lamellar st ructure, 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 le ss than that of SP diblock copolymer. Interfacial thickness of PSP, actuall y 2-vinylpyridine-styrene-d(8)-2-vinylpyridine) (PDP) triblock copolymer wa s measured by neu tron reflectivity and estimated to be 4.5 nm, which is es sentially the same as that for SP diblock copolymer interface. Alternativel y, the features of tricontinuous structure of ISP were determined to have c haracteristics of parallel surfaces to G-surface, which is one of the infin ite minimal surfaces, by transmission electron microscopy and small angle X -ray scattering. (C) 1999 Elsevier Science Ltd. All rights reserved.