Determination of Fddd phase boundary in polystyrene-block-polyisoprene diblock copolymer
Abstract
We previously reported the discovery of a novel bicontinuous microdomain structure with Fddd symmetry in polystyrene-block-polyisoprene (SI) diblock copolymer. In this study, we investigated the phase behavior of eight SI diblock copolymer samples having slightly different compositions (0.627<=fPI<=0.653) by SAXS and TEM to determine the phase boundary of the Fddd structure in the phase diagram of SI. The SI having the lowest fPI (= 0.627) showed only disorder-lamella (L) transition but no order-order transition. The SI having the largest fPI (= 0.653) showed disorder-gyroid (G)-L transition with decreasing temperature, but did not show Fddd phase. The other six SI samples having fPI values between these two exhibited disorder-G-Fddd-L transition with decreasing temperature. Consequently, we could determine the compositional region where Fddd phase is thermally stable, which is in good agreement with that predicted by SCFT.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2009
- Bibcode:
- 2009APS..MARA18002K