Atomistic simulations of mixtures of oligomers of polyisoprene and polystyrene were performed over a range of compositions and temperatures. The influence of mixing on structure and dynamics was investigated. Increasing polystyrene concentration slows down the dynamics considerably. The inhomogeneities in the dynamics are correlated with the local neighborhood of segments. A local surplus of polystyrene leads to a slower than average local dynamics and vice versa. Static and dynamic inhomogeneities are correlated on the segment level. The local length scale to influence the dynamics is on the order of 0.8-1 nm. Moreover, we find strong end effects on the dynamics of both components.