Structure and Dynamics of Nonionic Surfactant Aggregates in Layered Materials.
Régis GuéganEmmanuel VeronLydie Le ForestierMakoto OgawaSylvian CadarsPublished in: Langmuir : the ACS journal of surfaces and colloids (2017)
The aggregation of surfactants on solid surfaces as they are adsorbed from solution is the basis of numerous technological applications such as colloidal stabilization, ore flotation, and floor cleaning. The understanding of both the structure and the dynamics of surfactant aggregates applies to the development of alternative ways of preparing hybrid layered materials. For this purpose, we study the adsorption of the triethylene glycol mono n-decyl ether (C10E3) nonionic surfactant onto a synthetic montmorillonite (Mt), an aluminosilicate clay mineral for organoclay preparation with important applications in materials sciences, catalysis, wastewater treatment, or as drug delivery. The aggregation mechanisms follow those observed in an analogous natural Mt, with the condensation of C10E3 in a bilayer arrangement once the surfactant self-assembles in a lamellar phase beyond the critical micelle concentration, underlining the importance of the surfactant state in solution. Solid-state 1H nuclear magnetic resonance (NMR) at fast magic-angle spinning (MAS) and high magnetic field combined with1H-13C correlation experiments and different types of 13C NMR experiments selectively probes mobile or rigid moieties of C10E3 in three different aggregate organizations: (i) a lateral monolayer, (ii) a lateral bilayer, and (iii) a normal bilayer. High-resolution 1H{27Al} CP-1H-1H spin diffusion experiments shed light on the proximities and dynamics of the different fragments and fractions of the intercalated surfactant molecules with respect to the Mt surface. 23Na and 1H NMR measurements combined with complementary NMR data, at both molecular and nanometer scales, precisely pointed out the location of the C10E3 ethylene oxide hydrophilic group in close contact with the Mt surface interacting through ion-dipole or van der Waals interactions.
Keyphrases
- solid state
- magnetic resonance
- high resolution
- wastewater treatment
- drug delivery
- single molecule
- minimally invasive
- small molecule
- mass spectrometry
- room temperature
- antibiotic resistance genes
- computed tomography
- staphylococcus aureus
- electronic health record
- transition metal
- density functional theory
- escherichia coli
- liquid chromatography
- machine learning
- cancer therapy
- cystic fibrosis
- gold nanoparticles
- molecular dynamics
- fluorescence imaging
- aqueous solution
- candida albicans
- simultaneous determination