OBSERVED FRUSTRATION IN CONFINED BLOCK-COPOLYMERS

Symmetric, diblock copolymers confined between two solid surfaces were studied by neutron reflectivity. A multilayered morphology with an in tegral number of layers oriented parallel to the solid interfaces was found in all cases. The period of the confined multilayers deviated fr om the bulk period in a cyclic manner as a function of the confined fi lm thickness. A first-order transition occurred between the expanded a nd contracted states of the copolymer chains. The data suggest that th e deviation of the period from the bulk value decreases with increasin g separation distance.