Concentration Fluctuations in Homogeneous Diblock Copolymers.

In this paper, we report evidence of local concentration fluctuations in thermodynamically homogeneous diblock copolymers near the microphase separation transition (MST). Dielectric spectroscopy has been used to probe the local structure of a series of 1,4- polybutadiene/1,2-polybutadiene diblock copolymers with morphologies that ranged from well-ordered to disordered. Four transitions, corresponding to the primary (glass) and secondary transitions of each block, are observed in the dielectric loss spectrum of each copolymer studied.