The miscibility of polycarbonates (PC) with polystyrene (PS) appears to be closely related to chain dynamics. Among all polycarbonates, tetramethyl bisphenol-A polycarbonate (TMPC), is the only PC miscible with PS. The presence of the two methyl groups attached to each phenyl ring, hinder phenyl flips and this may be partly responsible for the formation of miscible blends with PS. The aim of the proposed experiment is to improve our understanding of molecular dynamics of polycarbonates (BPA-PC and TMPC). We also wish to investigate the changes in the motion of TMPC when blended with PS (deuterated).