In two homologous series of poly(fluoroalkyl methacrylate) (PFM) and poly(fluoroalkyl α-fluoroacrylate) (PFF)there were observed α above T g and γ relaxations below T g , which are assigned to reorientational motion of long segments and local molecular motion of fluoroalkyl side groups, respectively. As the length of the fluoroalkyl side groups are longer, the a relaxation gradually shifted to lower temperatures and the γ relaxation rapidly moved to higher temperatures, being very consistent with the well-known results in the homologous series of poly(alkyl methacrylate)