Tuning the position of head groups by surfactant design in mixed micelles of cationic and carbohydrate surfactants

Saikat Das; Edward Davis Oldham; Hans Joachim Lehmler; Barbara L. Knutson; Stephen E. Rankin

doi:10.1016/j.jcis.2017.10.066

Tuning the position of head groups by surfactant design in mixed micelles of cationic and carbohydrate surfactants

Saikat Das, Edward Davis Oldham, Hans Joachim Lehmler, Barbara L. Knutson, Stephen E. Rankin

Chemical and Materials Engineering

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Hypothesis Emerging applications of carbohydrate/cationic surfactant mixtures require not only synergistic mixing, but also accessible sugar headgroups at the exterior of micelles. A previous study showed that the glucoside headgroups of octyl-β-D-glucopyranoside aggregate at the interior of mixed micelles with equimolar cetyltrimethylammonium bromide rather than mixing with trimethylammonium groups at the corona. The current study tests the hypothesis that structural characteristics of the surfactants (the relative lengths of the alkyl tails and the type of linker) can be tuned to shift the carbohydrate groups to micelle surfaces. Experiments The structural arrangement of 30 mM equimolar mixed micelle solutions in D₂O is investigated using NMR. The dynamics in different regions are probed using ¹H spin-lattice (T₁) and spin-spin (T₂) relaxation measurements, and relative positioning by nuclear Overhauser effect spectroscopy (NOESY). Additional micellar properties are determined using solvatochromic fluorescent probes. Findings Matching surfactant alkyl tail lengths is found ineffective at “pushing out” the carbohydrate headgroups due to a large mismatch in interactions between the headgroups and D₂O. However, inserting a novel polar triazole group between the carbohydrate head group and the hydrophobic tail (e.g. in n-octyl-β-D-xylopyranoside) using click chemistry is able to “pull out” the carbohydrate, thus giving accessible sugar moieties at the surface of mixed micelles.

Original language	English
Pages (from-to)	428-438
Number of pages	11
Journal	Journal of Colloid and Interface Science
Volume	512
DOIs	https://doi.org/10.1016/j.jcis.2017.10.066
State	Published - Feb 15 2018

Bibliographical note

Funding Information:
This work was funded by the United States Department of Agriculture under grant number 68-3A75-7-608 and the U.S. National Science Foundation (grant no. CBET-0967381/0967390 ). All of the NMR experiments were performed in the NMR facility of the Department of Chemistry at the University of Kentucky. We thank John Layton of the NMR facility in the Department of Chemistry at the University of Kentucky for helpful discussions of the NMR experiments.

Publisher Copyright:
© 2017 Elsevier Inc.

Keywords

Click chemistry
Micellization
Mixing
Nuclear magnetic resonance
Self-assembly
Sugar surfactants
Supramolecular

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Biomaterials
Surfaces, Coatings and Films
Colloid and Surface Chemistry

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10.1016/j.jcis.2017.10.066

Cite this

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title = "Tuning the position of head groups by surfactant design in mixed micelles of cationic and carbohydrate surfactants",

abstract = "Hypothesis Emerging applications of carbohydrate/cationic surfactant mixtures require not only synergistic mixing, but also accessible sugar headgroups at the exterior of micelles. A previous study showed that the glucoside headgroups of octyl-β-D-glucopyranoside aggregate at the interior of mixed micelles with equimolar cetyltrimethylammonium bromide rather than mixing with trimethylammonium groups at the corona. The current study tests the hypothesis that structural characteristics of the surfactants (the relative lengths of the alkyl tails and the type of linker) can be tuned to shift the carbohydrate groups to micelle surfaces. Experiments The structural arrangement of 30 mM equimolar mixed micelle solutions in D2O is investigated using NMR. The dynamics in different regions are probed using 1H spin-lattice (T1) and spin-spin (T2) relaxation measurements, and relative positioning by nuclear Overhauser effect spectroscopy (NOESY). Additional micellar properties are determined using solvatochromic fluorescent probes. Findings Matching surfactant alkyl tail lengths is found ineffective at “pushing out” the carbohydrate headgroups due to a large mismatch in interactions between the headgroups and D2O. However, inserting a novel polar triazole group between the carbohydrate head group and the hydrophobic tail (e.g. in n-octyl-β-D-xylopyranoside) using click chemistry is able to “pull out” the carbohydrate, thus giving accessible sugar moieties at the surface of mixed micelles.",

keywords = "Click chemistry, Micellization, Mixing, Nuclear magnetic resonance, Self-assembly, Sugar surfactants, Supramolecular",

author = "Saikat Das and Oldham, {Edward Davis} and Lehmler, {Hans Joachim} and Knutson, {Barbara L.} and Rankin, {Stephen E.}",

note = "Funding Information: This work was funded by the United States Department of Agriculture under grant number 68-3A75-7-608 and the U.S. National Science Foundation (grant no. CBET-0967381/0967390 ). All of the NMR experiments were performed in the NMR facility of the Department of Chemistry at the University of Kentucky. We thank John Layton of the NMR facility in the Department of Chemistry at the University of Kentucky for helpful discussions of the NMR experiments. Publisher Copyright: {\textcopyright} 2017 Elsevier Inc.",

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doi = "10.1016/j.jcis.2017.10.066",

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AU - Oldham, Edward Davis

AU - Lehmler, Hans Joachim

AU - Knutson, Barbara L.

AU - Rankin, Stephen E.

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PY - 2018/2/15

Y1 - 2018/2/15

N2 - Hypothesis Emerging applications of carbohydrate/cationic surfactant mixtures require not only synergistic mixing, but also accessible sugar headgroups at the exterior of micelles. A previous study showed that the glucoside headgroups of octyl-β-D-glucopyranoside aggregate at the interior of mixed micelles with equimolar cetyltrimethylammonium bromide rather than mixing with trimethylammonium groups at the corona. The current study tests the hypothesis that structural characteristics of the surfactants (the relative lengths of the alkyl tails and the type of linker) can be tuned to shift the carbohydrate groups to micelle surfaces. Experiments The structural arrangement of 30 mM equimolar mixed micelle solutions in D2O is investigated using NMR. The dynamics in different regions are probed using 1H spin-lattice (T1) and spin-spin (T2) relaxation measurements, and relative positioning by nuclear Overhauser effect spectroscopy (NOESY). Additional micellar properties are determined using solvatochromic fluorescent probes. Findings Matching surfactant alkyl tail lengths is found ineffective at “pushing out” the carbohydrate headgroups due to a large mismatch in interactions between the headgroups and D2O. However, inserting a novel polar triazole group between the carbohydrate head group and the hydrophobic tail (e.g. in n-octyl-β-D-xylopyranoside) using click chemistry is able to “pull out” the carbohydrate, thus giving accessible sugar moieties at the surface of mixed micelles.

AB - Hypothesis Emerging applications of carbohydrate/cationic surfactant mixtures require not only synergistic mixing, but also accessible sugar headgroups at the exterior of micelles. A previous study showed that the glucoside headgroups of octyl-β-D-glucopyranoside aggregate at the interior of mixed micelles with equimolar cetyltrimethylammonium bromide rather than mixing with trimethylammonium groups at the corona. The current study tests the hypothesis that structural characteristics of the surfactants (the relative lengths of the alkyl tails and the type of linker) can be tuned to shift the carbohydrate groups to micelle surfaces. Experiments The structural arrangement of 30 mM equimolar mixed micelle solutions in D2O is investigated using NMR. The dynamics in different regions are probed using 1H spin-lattice (T1) and spin-spin (T2) relaxation measurements, and relative positioning by nuclear Overhauser effect spectroscopy (NOESY). Additional micellar properties are determined using solvatochromic fluorescent probes. Findings Matching surfactant alkyl tail lengths is found ineffective at “pushing out” the carbohydrate headgroups due to a large mismatch in interactions between the headgroups and D2O. However, inserting a novel polar triazole group between the carbohydrate head group and the hydrophobic tail (e.g. in n-octyl-β-D-xylopyranoside) using click chemistry is able to “pull out” the carbohydrate, thus giving accessible sugar moieties at the surface of mixed micelles.

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KW - Self-assembly

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KW - Supramolecular

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Tuning the position of head groups by surfactant design in mixed micelles of cationic and carbohydrate surfactants

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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