Model ABC Triblock Copolymers and Blends Near the Order-disorder Transition
- University of Minnesota
- ORNL
We report differences in the thermodynamic behavior of compositionally symmetric ABC and BAC triblock copolymers near the order-disorder transition temperature and of binary ABC/BAC copolymer blends: poly(styrene-b-isoprene-b-dimethylsiloxane) (SID) and ISD with segment volume fractions near 0.33 and similar molecular weight disorder at different temperatures and from different ordered-state symmetries. Blends of symmetric SID and ISD molecules with molecular weights near 10K are miscible and form a gyroid morphology over a wide range of blend compositions. Flory-Huggins interaction parameters for this ABC system allow a detailed interpretation of SAXS, SANS, and DMS measurements. Symmetric SID disorders from the lamellar state, while ISD disorders from hexagonally packed cylinders of D blocks in a mixed matrix of S and I blocks. Block mixing occurs to reduce the number of S-D interactions forced by chemical connectivity in ISD. This drive to minimize unfavorable interactions is the underlying cause of the results outlined in this report.
- Research Organization:
- Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
- Sponsoring Organization:
- SC USDOE - Office of Science (SC)
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1003254
- Journal Information:
- Macromolecules, Journal Name: Macromolecules Journal Issue: 8 Vol. 35; ISSN 1520-5835; ISSN 0024-9297
- Country of Publication:
- United States
- Language:
- English
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