| 초록 |
The phase behavior of symmetric styrene-isoprene (SI) diblock copolymers in selective solvents at the vicinity of order-disorder transition (ODT) was investigated by small-angle x-ray scattering (SAXS) and rheology. The change in G’ and G” as a function of frequency clearly represents the solid-like transient behavior immediately after ODT from cylindrical microdomain. This implies that the ODT is induced by the spontaneous formation of spheres due to the dissociation of cylinders. The temperature range of the transient phase is found to be quite dependent on the solvent-selectivity, which is confirmed by three kinds of solvents. The induction time for the initiation of massive undulation of cylindrical domains to split into disordered spheres is also closely related to the solvent selectivity. In order to understand morphological changes in more detail, one of the blocks is deuterated, i.e., PS-dPI and dPS-PI, and the contrast matching technique, in which scattering length density (SLD) of solvent used is identical to the SLD of corona chains was applied. |
