A comprehensive, time-resolved SANS investigation of temperature-change-induced sponge-to-lamellar and lamellar-to-sponge phase transformations in comparison with 2H -NMR results
(2007) In European Physical Journal E. Soft Matter 24(3). p.277-295- Abstract
- Time-resolved small-angle neutron scattering (TR-SANS) was employed to observe temperature-induced phase transitions from the sponge (L-3 to the lamellar ( L (alpha) phase, and vice versa, in the water-oil (n-decane)-non-ionic surfactant (C12E5 system using both bulk and film contrast. Samples of different bilayer volume fractions phi and solvent viscosities eta were investigated applying various amplitudes of temperature jump Delta T . The findings of a previous H-2-NMR study could be confirmed, where the lamellar phase formation was determined to occur through a nucleation and growth process, while it was concluded that the L-3-phase develops in a mechanistically different and more rapid manner involving uncorrelated passage formation.... (More)
- Time-resolved small-angle neutron scattering (TR-SANS) was employed to observe temperature-induced phase transitions from the sponge (L-3 to the lamellar ( L (alpha) phase, and vice versa, in the water-oil (n-decane)-non-ionic surfactant (C12E5 system using both bulk and film contrast. Samples of different bilayer volume fractions phi and solvent viscosities eta were investigated applying various amplitudes of temperature jump Delta T . The findings of a previous H-2-NMR study could be confirmed, where the lamellar phase formation was determined to occur through a nucleation and growth process, while it was concluded that the L-3-phase develops in a mechanistically different and more rapid manner involving uncorrelated passage formation. Likewise, the kinetic trends of the nucleation and growth transition (decreased transition time with increase of phi and Delta T were witnessed once again. Additionally, NMR and SANS data that demonstrate a strong dependency of that process on solvent viscosity eta are presented. Contrariwise, it is made evident via both SANS and NMR results that the L-alpha-to-L-3 transition time is independent (within experimental sensitivity) of the varied parameters (phi, Delta T, eta) . Unusual scattering evolution in one experiment, originating from a highly ordered lamellar phase, intriguingly hints that a major rate determining factor is the disruption of long-range order. Furthermore, the bulk contrast investigations give insight into structure peak shifts/development during the transitions, while the film contrast experiments prove the bilayer thickness to be constant throughout the phase transitions and show that there is no evidence for a change in the short-range order of the bilayer structure. The latter was considered possible, due to the different topology of the L-3 and L-alpha phases. Lastly, an unexpected yet consistent appearance of anisotropic scattering is detected in the L-3-to-L-alpha transitions. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1026745
- author
- Gotter, Martin ; Sottman, Thomas ; Baciu, Magdalena ; Olsson, Ulf LU ; Wennerström, Håkan LU and Strey, Reinhard
- organization
- publishing date
- 2007
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- KINETICS, BILAYERS, BEHAVIOR, MICROEMULSIONS, L3 PHASES, DILUTE LAMELLAR, C12E6/D2O SYSTEM, NONIONIC SURFACTANT, ANGLE NEUTRON-SCATTERING, MEMBRANE-FUSION
- in
- European Physical Journal E. Soft Matter
- volume
- 24
- issue
- 3
- pages
- 277 - 295
- publisher
- Springer
- external identifiers
-
- wos:000251770200009
- scopus:37449013899
- ISSN
- 1292-8941
- DOI
- 10.1140/epje/i2007-10238-8
- language
- English
- LU publication?
- yes
- id
- 7e7d1ada-66a4-4deb-b654-a1e15852fcb5 (old id 1026745)
- date added to LUP
- 2016-04-01 17:06:26
- date last changed
- 2022-01-29 00:23:02
@article{7e7d1ada-66a4-4deb-b654-a1e15852fcb5, abstract = {{Time-resolved small-angle neutron scattering (TR-SANS) was employed to observe temperature-induced phase transitions from the sponge (L-3 to the lamellar ( L (alpha) phase, and vice versa, in the water-oil (n-decane)-non-ionic surfactant (C12E5 system using both bulk and film contrast. Samples of different bilayer volume fractions phi and solvent viscosities eta were investigated applying various amplitudes of temperature jump Delta T . The findings of a previous H-2-NMR study could be confirmed, where the lamellar phase formation was determined to occur through a nucleation and growth process, while it was concluded that the L-3-phase develops in a mechanistically different and more rapid manner involving uncorrelated passage formation. Likewise, the kinetic trends of the nucleation and growth transition (decreased transition time with increase of phi and Delta T were witnessed once again. Additionally, NMR and SANS data that demonstrate a strong dependency of that process on solvent viscosity eta are presented. Contrariwise, it is made evident via both SANS and NMR results that the L-alpha-to-L-3 transition time is independent (within experimental sensitivity) of the varied parameters (phi, Delta T, eta) . Unusual scattering evolution in one experiment, originating from a highly ordered lamellar phase, intriguingly hints that a major rate determining factor is the disruption of long-range order. Furthermore, the bulk contrast investigations give insight into structure peak shifts/development during the transitions, while the film contrast experiments prove the bilayer thickness to be constant throughout the phase transitions and show that there is no evidence for a change in the short-range order of the bilayer structure. The latter was considered possible, due to the different topology of the L-3 and L-alpha phases. Lastly, an unexpected yet consistent appearance of anisotropic scattering is detected in the L-3-to-L-alpha transitions.}}, author = {{Gotter, Martin and Sottman, Thomas and Baciu, Magdalena and Olsson, Ulf and Wennerström, Håkan and Strey, Reinhard}}, issn = {{1292-8941}}, keywords = {{KINETICS; BILAYERS; BEHAVIOR; MICROEMULSIONS; L3 PHASES; DILUTE LAMELLAR; C12E6/D2O SYSTEM; NONIONIC SURFACTANT; ANGLE NEUTRON-SCATTERING; MEMBRANE-FUSION}}, language = {{eng}}, number = {{3}}, pages = {{277--295}}, publisher = {{Springer}}, series = {{European Physical Journal E. Soft Matter}}, title = {{A comprehensive, time-resolved SANS investigation of temperature-change-induced sponge-to-lamellar and lamellar-to-sponge phase transformations in comparison with 2H -NMR results}}, url = {{http://dx.doi.org/10.1140/epje/i2007-10238-8}}, doi = {{10.1140/epje/i2007-10238-8}}, volume = {{24}}, year = {{2007}}, }