  The structure of polymer coils near interfaces between coexisting phases of
symmetrical polymer mixtures (AB) is discussed, as well as the structure of
symmetric diblock copolymers of the same chain length N adsorbed at the
interface. The problem is studied by Monte Carlo simulations of the bond
fluctuation model on the simple cubic lattice, using massively parallel
computers (CRAY T3D). While homopolymer coils in the strong segregation limit
are oriented parallel to the interface, the diblocks form ``dumbbells''
oriented perpendicular to the interface. However, in the dilute case
(``mushroom regime'' rather than ``brush regime''), the diblocks are only
weakly stretched. Distribution functions for monomers at the chain ends and in
the center of the polymer are obtained, and a comparison to the self consistent
field theory is made.
