Dielectric study of dynamical heterogeneity in blends of polyethers

We report the dielectric study of dynamical heterogeneity in miscible polymer blends composed of four kinds of polyethers, i.e., poly(butylene oxide) (PBO), poly(isopropylglycidyl ether) (PiPGE), poly(n-butylglycidyl ether) (PnBGE), and poly(t-butylglycidyl ether) (PtBGE). All polyethers exhibit both the dielectric normal mode relaxations due to fluctuation of the end-to-end vector and the segmental mode due to local motions. In blends composed of polyethers, the loss curves for the segmental modes are unimodal but are asymmetrical when the composition becomes asymmetrical, namely 75/25 and 25/75. The asymmetrical loss curve indicates that the loss curve consists of the fast and slow modes. We have resolved the loss curves into the fast- and slow modes by curve fitting assuming that the segmental modes are composed of two ε″ curves. Thus we have estimated the separation of the fast and slow modes. The separation is approximately proportional to the difference of the glass transition temperatures of the components.