Phase structure of solution cast films of α-methylstyrene/butadiene/styrene block copolymers

The phase structure of solvent cast films of α-methylstyrene/butadiene/styrene of differing compositions was investigated using physical methods. Both dynamic mechanical and differential scanning calorimetry measurements exhibited a single high temperature transition at 150°C. The transition has been shown to originate from a composite domain of the two glassy end blocks. Light scattering measurements showed that these domains varied in size from 0·35 to 0·40 μm and that they are randomly arranged within the butadiene matrix. The results are compared with the results of similar studies of ABA systems.