Morphological behavior of A(5)B miktoarm star block copolymers

A morphological study of three A(5)B, six-arm miktoarm star block copolymer s is presented. The miktoarm stars are comprised of five arms of polyisopre ne and one arm of polystyrene joined together at: a single junction point. The strong segregation limit theory for the morphological behavior of mikto arm stars predicts that these materials should form cylindrical (two sample s) and lamellar (one sample) morphologies, but only lamellar morphologies w ere observed by TEM and SAXS. These results are similar to previously repor ted discrepancies between miktoarm star morphological behavior and the pred ictions of the theory. Combining the data of this study with that of previo us morphological studies of miktoarm star materials, we can track the incre asing discrepancy between the experimentally observed morphology and theore tical predictions as the molecular asymmetry parameter, epsilon, increases. The ASB materials in this study were also observed to form exceptionally w ell-ordered morphologies.