Moore, Jackson E; McCoy, Thomas M; Marlow, Joshua B; Pottage, Matthew J; Mudie, Stephen T; Pearson, Graeme R; Wilkinson, Brendan L; Tabor, Rico F

Author(s)

Moore, Jackson E

McCoy, Thomas M

Marlow, Joshua B

Pottage, Matthew J

Mudie, Stephen T

Pearson, Graeme R

Wilkinson, Brendan L

Tabor, Rico F

Publication Date

2019-03-22

Abstract

Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Herein, we explore the phase behavior of seven novel carbohydrate-based surfactants (CBS) containing a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and cis-unsaturated (C18:1) alkyl chains. At high aqueous concentrations, these glycolipid-like surfactants transition into a variety of lyotropic liquid crystalline phases following an expected concentration phase sequence: hexagonal (H₁) -> bicontinuous cubic (V₁) -> lamellar (Lα). Using polarizing light microscopy (PLM), a binary (surfactant–water) phase diagram for each surfactant was constructed across a temperature range (25–80 °C) revealing thermotropic behavior and a broadening of liquid crystal phase regions with increasing alkyl chain length. There was also a significant difference between saturated and unsaturated alkyl chains, due to the cis-unsaturated ‘statistical bend’ lowering the melting point. Small-angle X-ray scattering (SAXS) measurements were performed to characterize the liquid crystal phases, identifying highly-ordered p6m; Ia3d, and Lα crystallographic space-groups with up to 7 resolved Bragg peaks, likely due to the highly anisometric nature of the TEG-linked surfactants. The phases were shown to be more numerous and exhibited greater thermalstability compared to well-characterized alkyl glucoside surfactants lacking an oligoethylene spacer in the literature. Finally, the characteristic dimensions of each phase were determined to enable visualization of the internal microstructures, providing insight into the impact of molecular shape and the distribution of hydro-philicity/phobicity on the formation and stability of liquid crystalline mesophases.

Citation

Journal of Colloid and Interface Science, v.540, p. 410-419

ISSN

1095-7103

0021-9797

Pubmed ID

30665167

Link

https://hdl.handle.net/1959.11/26640

Publisher

Academic Press

Title

Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants

Type of document

Journal Article

Entity Type

Publication

Author(s)	Moore, Jackson E McCoy, Thomas M Marlow, Joshua B Pottage, Matthew J Mudie, Stephen T Pearson, Graeme R Wilkinson, Brendan L Tabor, Rico F
Publication Date	2019-03-22
Abstract	Carbohydrates are appealing non-ionic surfactant head-groups as they are naturally abundant, generally biocompatible and biodegradable, and readily functionalized. Herein, we explore the phase behavior of seven novel carbohydrate-based surfactants (CBS) containing a tri-ethylene glycol (TEG) linker between a glucose head-group and alkyl tail-group, with linear saturated (C8–18) and cis-unsaturated (C18:1) alkyl chains. At high aqueous concentrations, these glycolipid-like surfactants transition into a variety of lyotropic liquid crystalline phases following an expected concentration phase sequence: hexagonal (H₁) -> bicontinuous cubic (V₁) -> lamellar (Lα). Using polarizing light microscopy (PLM), a binary (surfactant–water) phase diagram for each surfactant was constructed across a temperature range (25–80 °C) revealing thermotropic behavior and a broadening of liquid crystal phase regions with increasing alkyl chain length. There was also a significant difference between saturated and unsaturated alkyl chains, due to the cis-unsaturated ‘statistical bend’ lowering the melting point. Small-angle X-ray scattering (SAXS) measurements were performed to characterize the liquid crystal phases, identifying highly-ordered p6m; Ia3d, and Lα crystallographic space-groups with up to 7 resolved Bragg peaks, likely due to the highly anisometric nature of the TEG-linked surfactants. The phases were shown to be more numerous and exhibited greater thermalstability compared to well-characterized alkyl glucoside surfactants lacking an oligoethylene spacer in the literature. Finally, the characteristic dimensions of each phase were determined to enable visualization of the internal microstructures, providing insight into the impact of molecular shape and the distribution of hydro-philicity/phobicity on the formation and stability of liquid crystalline mesophases.
Citation	Journal of Colloid and Interface Science, v.540, p. 410-419
ISSN	1095-7103 0021-9797
Pubmed ID	30665167
Link	https://hdl.handle.net/1959.11/26640
Publisher	Academic Press
Title	Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants
Type of document	Journal Article
Entity Type	Publication

Rich liquid crystal phase behavior of novel alkyl-tri(ethylene glycol)-glucoside carbohydrate surfactants

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