Dielectric properties of diblock copolymers

Dielectric spectroscopy was used to probe a series of diblock copolymers which have widely different degrees of order. The 1,2-polybutadiene/1,4-polybutadiene diblock copolymer system was chosen because both ordered and disordered morphologies can be obtained near room temperature. It is observed that the local motions of the high-temperature component are greatly enhanced in the block copolymer over the homopolymer. Also found is evidence of local concentration fluctuations of the low-temperature component which are large enough to exhibit a glass transition, even in samples that appear to be completely disordered on the length scales probed by SANS and rheological measurements.