  Computer simulation studies on the miscibility behavior and single chain
properties in binary polymer blends are reviewed. We consider blends of various
architectures in order to identify important architectural parameters on a
coarse grained level and study their qualitative consequences for the
miscibility behavior. The phase diagram, the relation between the exchange
chemical potential and the composition, and the intermolecular paircorrelation
functions for symmetric blends of linear chains, blends of cyclic polymers,
blends with an asymmetry in cohesive energies, blends with different chain
lengths, blends with distinct monomer shapes, and blends with a stiffness
disparity between the components are discussed. We investiagte the temperature
and composition dependence of the single chain conformations in symmetric and
asymmetric blends and compare our findings to scaling arguments and detailed
SCF calculations.
  Two aspects of the single chain dynamics in blends are discussed: the
dynamics of short non--entangled chains in a binary blend and irreversible
reactions of a small fraction of reactive polymers at a strongly segregated
interface. Pertinent off-lattice simulations and analytical theories are
briefly discussed.
