Abstract
A versatile coupling reaction for the preparation of polybutadiene- poly(hexafluoropropylene oxide) (BF) diblock copolymers is described. Six diblock copolymers with different block lengths were characterized by nuclear magnetic resonance spectroscopy and size exclusion chromatography; all six had total molecular weights below 15,000. Microphase separation of the block copolymers in the bulk state was established by small-angle X-ray scattering (SAXS) and differential scanning calorimetry. SAXS data suggest that the diblocks are characterized by an unusually large Flory-Huggins interaction parameter, χ, on the order of 10. However, extraction of χ from the order-disorder transition gave large (order 1) but significantly different values, thereby suggesting that these copolymers are too small and too strongly interacting to be described by block copolymer mean-field theory. Dynamic light scattering was used to analyze dilute solutions of the title block copolymers in four selective organic solvents; the sizes of the micelles formed were solvent dependent. The micellar aggregates were large and nonspherical, and this is also attributed to the high degree of incompatibility between the two immiscible blocks.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3685-3694 |
| Number of pages | 10 |
| Journal | Journal of Polymer Science, Part B: Polymer Physics |
| Volume | 43 |
| Issue number | 24 |
| DOIs | |
| State | Published - Dec 15 2005 |
Keywords
- Dynamic light scattering
- Fluorinated block copolymers
- Micelles
- Small-angle X-ray scattering
- Super strong segregation