Ordering Transitions of Fluoroalkyl-Ended Poly(ethylene glycol): Rheology and SANS
Abstract
Aqueous solutions of associative polymers consisting of poly(ethylene glycol) (PEG) (6K or 10K g/mol) terminated at both ends with hydrophobic fluoroalkyl segments, −(CH_2)_2CnF_(2n+1) (n = 6, 8, or 10), exhibit ordering transitions with increasing concentration. The hydrophobic cores of the micelle-like aggregates order into a body-centered-cubic (bcc) structure, as observed by small-angle neutron scattering. The aggregation number of the hydrophobic core N_(ag) is determined by the length of the hydrophobic end group and is insensitive to polymer concentration or temperature. Ordering is enhanced by reducing PEG length for a given end group (hence, similar N_(ag)) or by increasing end group length (larger N_(ag)) for a given PEG length. This micelle packing effect is manifested in changes in the viscoelastic properties. Specifically, the single-relaxation behavior in the dynamic moduli changes upon ordering as a new low-frequency elastic plateau appears, and in creep a linear response changes to yielding behavior.
Additional Information
© 2002 American Chemical Society. Received 18 October 2001. Published online 27 April 2002. Published in print 21 May 2002. This research was supported in part by a grant from NSF (CTS-9729443), a graduate fellowship from the Korean Ministry of Education (Giyoong Tae), and the MRSEC Program of NSF (DMR-0080065). This work benefitted from the use of the IPNS at Argonne National Laboratory (US DoE-BES contract W-31-109-ENG-38).Additional details
- Eprint ID
- 79239
- Resolver ID
- CaltechAUTHORS:20170720-084036432
- NSF
- CTS-9729443
- Ministry of Education (Korea)
- NSF
- DMR-0080065
- Department of Energy (DOE)
- W-31-109-ENG-38
- Created
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2017-07-20Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field