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- Title
A Vesicle-to-Worm Transition Provides a New High-Temperature Oil Thickening Mechanism.
- Authors
Derry, Matthew J.; Mykhaylyk, Oleksandr O.; Armes, Steven P.
- Abstract
Diblock copolymer vesicles are prepared via RAFT dispersion polymerization directly in mineral oil. Such vesicles undergo a vesicle-to-worm transition on heating to 150 °C, as judged by TEM and SAXS. Variable-temperature 1H NMR spectroscopy indicates that this transition is the result of surface plasticization of the membrane-forming block by hot solvent, effectively increasing the volume fraction of the stabilizer block and so reducing the packing parameter for the copolymer chains. The rheological behavior of a 10 % w/w copolymer dispersion in mineral oil is strongly temperature-dependent: the storage modulus increases by five orders of magnitude on heating above the critical gelation temperature of 135 °C, as the non-interacting vesicles are converted into weakly interacting worms. SAXS studies indicate that, on average, three worms are formed per vesicle. Such vesicle-to-worm transitions offer an interesting new mechanism for the high-temperature thickening of oils.
- Subjects
DIBLOCK copolymers; BLOCK copolymers; POLYMERS; POLYMERIZATION; MINERAL oils; SPECTRUM analysis
- Publication
Angewandte Chemie International Edition, 2017, Vol 56, Issue 7, p1746
- ISSN
1433-7851
- Publication type
Article
- DOI
10.1002/anie.201609365