Microphase separation of diblock copolymers consisting of polystyrene and acid-functionalized poly(propylene imine) dendrimers

Diblock copolymers consisting of polystyrene and acid-functionalized poly(propylene imine) dendrimers have been found to self-assemble spontaneously into regular microdomains. The hybride dendrimer-linear chain block copolymers yield highly asymmetric molecules which display an aggregation behavior at the strong segregation limit that differs from the well-known all-linear block copolymers. The morphological features are used to determine the relationship between the architecture of the blocks and the arrangement of the molecules in the bulk. Microlattice formation of these materials was examined by using small-angle X-ray scattering and transmission electron microscopy techniques. By increasing the dendrimer generation, the structures changed from hexagonally packed cylinders with polystyrene as matrix to lamellar phases of different packing density. Good agreement between TEM and SAXS results was obtained, and the microlattice morphology was found to be highly dependent on the dendrimer generation.