Chain conformations of ABA triblock coplymers in microphase-separated structures for SANS

Single chain conformations of center block, polystyrene, of poly(2-vinylpyridine-b-styrene-b-2-vinylpyridine)(PSP) triblock copolymers of the ABA type in bulk were measured by small angle neutron scattering (SANS), while microphase separation structures were studied by small angle X-ray Scattering (SAXS) and transmission electron microscopy (TEM). From the morphological observations, PSP block copolymers have confirmed to have alternating lamellar structure both when φs = 0.33 and φs = 0.5, where φs is the volume fraction of polystyrene blocks. It was also clarified that the chain dimension of center blocks of sample with φs = 0.33 is smaller than that of sample with φs = 0.5. This result may mean that the center blocks have bridge-righ conformation when φs = 0.33 while they have loop-rich conformation when φs = 0.5. (author)