Recent advances in resolving kinetic and dynamic processes at the air/water interface using specular neutron reflectometry

Campbell, Richard A.

doi:10.1016/j.cocis.2018.06.002

Cited by 45 publications

(38 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Scattering contrast arises from a difference between the SLDs of neighboring media. Reflectometry studies with a focus on the structure of bare interfaces between water and hydrophobic media are often carried out with two types of experimental configurations offering strong contrast between the two bulk media, as schematically illustrated in Figure 1A: (i) Hydrogenous or deuterated water (H2O or D2O, respectively) or mixtures thereof contacting air or gas [33,42,43], or (ii) H2O or D2O contacting hydrogenous hydrocarbon chains in the form of oil [5,34,35,36,37,38,39,40,41] or of oil-like molecules grafted to a solid surface [44]. Contrast-optimized NR studies dealing with hydrophobized solids [45,46,47] involved considerable structural complexity, making interpretation difficult in view of the limited Qz-range [46].…”

Section: Results and Discussionmentioning

confidence: 99%

“…To this end, the SLD of hydrocarbon chains can be considered a feature common to all common surfactants. Reflectometry has been used routinely to quantify the interfacial adsorption of molecules to air/water interfaces [33] and more recently also to oil/water (O/W) interfaces [5,34,35,36,37,38,39,40,41]. But so far there have been no studies evidencing the accumulation of surfactant impurities at bare water/hydrophobic interfaces.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces

et al. 2019

Self Cite

View full text Add to dashboard Cite

Bare interfaces between water and hydrophobic media like air or oil are of fundamental scientific interest and of great relevance for numerous applications. A number of observations involving water/hydrophobic interfaces have, however, eluded a consensus mechanistic interpretation so far. Recent theoretical studies ascribe these phenomena to an interfacial accumulation of charged surfactant impurities in water. In the present work, we show that identifying surfactant accumulation with X-ray reflectometry (XRR) or neutron reflectometry (NR) is challenging under conventional contrast configurations because interfacial surfactant layers are then hardly visible. On the other hand, both XRR and NR become more sensitive to surfactant accumulation when a suitable scattering length contrast is generated by using fluorinated oil. With this approach, significant interfacial accumulation of surfactant impurities at the bare oil/water interface is observed in experiments involving standard cleaning procedures. These results suggest that surfactant impurities may be a limiting factor for the investigation of fundamental phenomena involving water/hydrophobic interfaces.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…In this case, an exponential term is applied that reduces the reflectance from each interface with increasing Qz according to the formulism of de Boer. 49 The MINUIT minimization package 50 used in Aurore provides uncertainty values from evaluation of the variation of χ 2 upon changes in the parameter values, where = ) ) (5) and N is the number of experimental points, Np is the number of free parameters, Rexp and Rtheo are the experimental and theoretical reflectivity, respectively, and εi is the error on the i th experimental point. 52 Reported values of the uncertainties account for any correlation between parameters.…”

Section: = (4)mentioning

confidence: 99%

“…Recent advances in instrumentation have meant that it is now possible to resolve the surface excess of a single deuterated species on the second time scale and the composition of a binary mixture involving only one deuterated component on the minute time scale. 3,4,5 Nowadays, NR provides routine insight into complex systems in soft matter and biology. 6,7 It is most common to treat experimental reflectivity data through fitting models using the optical matrix or Parratt formulism for stratified media.…”

Section: Introductionmentioning

confidence: 99%

Structure of surfactant and phospholipid monolayers at the air/water interface modeled from neutron reflectivity data

Campbell

Saaka

Shao

et al. 2018

Journal of Colloid and Interface Science

Self Cite

View full text Add to dashboard Cite

Specular neutron reflectometry is a powerful technique to resolve interfacial compositions and structures in soft matter. Surprisingly however, even after several decades, a universal modeling approach for the treatment of data of surfactant and phospholipid monolayers at the air/water interface has not yet been established. To address this shortcoming, first a systematic evaluation of the suitability of different models is presented. The result is a comprehensive validation of an optimum model, which is evidently much needed in the field, and which we recommend as a starting point for future data treatment. While its limitations are openly discussed, consequences of failing to take into account various key aspects are critically examined and the systematic errors quantified. On the basis of this physical framework, we go on to show for the first time that neutron reflectometry can be used to quantify directly in situ at the air/water interface the extent of acyl chain compaction of phospholipid monolayers with respect to their phase. The achieved precision of this novel quantification is ∼10%. These advances together enhance significantly the potential for exploitation in future studies data from a broad range of systems including those involving synthetic polymers, proteins, DNA, nanoparticles and drugs.

show abstract

“…An overview over recent advances in resolving kinetic and dynamic processes at the air-water interface using NR can be found in ref. [59]. More recently, kinetic measurements of the ageing (nitrate radical oxidation) of a monolayer model for marine aerosols (galactocerebrosides (GCB)) have been combined with in-situ IRRAS [60]• (Fig.…”

Section: Recent Applicationsmentioning

confidence: 99%

Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems

Skoda

2019

Current Opinion in Colloid & Interface Science

View full text Add to dashboard Cite

Many interesting physical, chemical and biological phenomena occur at interfaces between nanometre scale layers of soft condensed matter. Theses often complex systems lend themselves to study by X-ray (XRR) and neutron reflectivity (NR). The application of these techniques to such systems is extremely wide spread and provides unique insights into their structure and dynamics. This review presents a snapshot of recent activity in this research area and identifies trends in the application of XRR and NR to novel, unusual or highly complex sample systems. Although the majority of research using these techniques is investigating variations on 'traditional' systems, supported by progress in instrumentation, advance sample environment and computational tools, NR and XRR have begun to produce singular insights in areas such as atmospheric science, real biological systems (cells and bacteria), oil-water interfaces or industrial problems (rheology, packaging or durability of nano-materials).

show abstract

Recent advances in resolving kinetic and dynamic processes at the air/water interface using specular neutron reflectometry

Cited by 45 publications

References 68 publications

Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces

Reflectometry Reveals Accumulation of Surfactant Impurities at Bare Oil/Water Interfaces

Structure of surfactant and phospholipid monolayers at the air/water interface modeled from neutron reflectivity data

Recent developments in the application of X-ray and neutron reflectivity to soft-matter systems

Contact Info

Product

Resources

About