Relaxation in block copolymer interfacial regions.

We have used DSC experiments to study the effect of annealing on the interfacial regions of a microphase-separated triblock copolymer. Broad annealing peaks are observed within hours at annealing temperatures between the glass transition temperatures of the blocks. We attribute these features to an enthalpy relaxation mechanism which affects portions of the interfacial material. The interface can be modeled as a series of homogeneous fractions that have glass transition temperatures intermediate to those of the blocks, and each fraction contributes independently to observed excess enthalpy.