Unexpected observation of an intermediate hexagonal phase upon fluid-to-gel transition: SDS self-assembly in glycerol

Lauren Matthews, Michael C Stevens, Ralf Schweins, Paul Bartlett, Andrew. J Johnson, Robert Sochon, Wuge H Briscoe*

*Corresponding author for this work

Research output: Contribution to journalLetter (Academic Journal)peer-review

1 Citation (Scopus)
79 Downloads (Pure)

Abstract

Understanding morphological transformations upon temperature-induced mesophase transitions offers mecha-nistic insights into the self-assembly process. We have recently reported the unexpected formation of a micro-fibrillar lamellar gel in SDS-glycerol mixtures above a critical gelation concentration (CGC) as low as ~2 wt%. The gel phase comprised a fibrillar structure on the microscale and a lamellar structure on the nanoscale. Here, the nanoscopic structure of the gel as a function of temperature was probed with small-angle neutron scattering (SANS). The gel underwent a gel-to-fluid transition at a critical gelation temperature, TGC =45 ◦C, forming cylindrical micelles at elevated temperatures. Upon cooling, a hexagonal phase formed at ~TGC, evident from the SANS Bragg peaks. This hexagonal phase upon the fluid-to-gel transition sheds light on the gelation mechanism, in which self-assembled SDS micelles undergo a cylindrical-to-lamellar morphological transition via a hexagonal phase. This unprecedented observation also highlights the complexity of self-assembly in nonaqueous hydrogen- bonding rich media.
Original languageEnglish
Article number100342
Number of pages5
JournalColloid and Interface Science Communications
Volume40
Early online date13 Dec 2020
DOIs
Publication statusPublished - 1 Jan 2021

Bibliographical note

Funding Information:
We acknowledge the Institut Laue-Langevin for the awarded beamtime under experiment number: 9-10-1586 [DOI https://doi.org/10.5291/ILL-DATA.9-10-1586 ]. We acknowledge ISIS Muon and Neutron source for the awarded beamtime under experiment number: 1810629 . L.M. was supported by a joint studentship through the Bristol Centre for Functional Nanomaterials ( Engineering and Physical Science Research Council (EPSRC) EP/L016648/1 ) and GlaxoSmithKline, and M.C.S. by a joint studentship through Infineum and EPSRC Doctoral Training Partnership Industrial and International Leverage Fund.

Funding Information:
We acknowledge the Institut Laue-Langevin for the awarded beamtime under experiment number: 9-10-1586 [DOI https://doi.org/10.5291/ILL-DATA.9-10-1586]. We acknowledge ISIS Muon and Neutron source for the awarded beamtime under experiment number: 1810629. L.M. was supported by a joint studentship through the Bristol Centre for Functional Nanomaterials (Engineering and Physical Science Research Council (EPSRC) EP/L016648/1) and GlaxoSmithKline, and M.C.S. by a joint studentship through Infineum and EPSRC Doctoral Training Partnership Industrial and International Leverage Fund.

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • Glycerol
  • SDS
  • Surfactant mesophases
  • Nonaqueous H-bonding solvents
  • Small-angle neutron scattering
  • Self-assembly
  • Gelation
  • Low molecular-weight gels
  • Lamellar phase
  • Hexagonal phase

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