Block copolymers near the microphase separation transition. 4. Dielectric spectroscopy.

Recently a model set of 1,4/1,2-polybutadiene diblock copolymers was prepared and studied near the microphase separation transition using differential scanning calorimetry, small-angle neutron scattering and rheology. In this study dielectric spectroscopy is used to probe the molecular motions in the diblock copolymers and compare them with transitions in 1,2 and 1,4 homopolymers. The diblock copolymers show two glass transitions and two secondary transitions which can be directly related to the alpha and beta transitions in the 1,2 and 1,4 homopolymers. Interactions between the 1,2 and 1,4 segments have a more profound effect on the transitions of 1,2 polybutadiene, the higher transition temperature species.