The Role of Interfacial Molecular Structure in the Adsorption of Ions at the Liquid−Liquid Interface

McFearin, Cathryn L.; Richmond, Geraldine L.

doi:10.1021/jp906616c

Cited by 48 publications

(104 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is identical for what we observed for PAA (21). The disappearing CH modes in all cases are replaced by an interfacial spectrum that resembles the spectra obtained in previous studies of the neat CCl 4 -water interface (16,37), where a prominent signal from the free OH stretching mode around 3;700 cm −1 appears, corresponding to interfacial water modes and a polymer free interface.…”

Section: Adsorption Of Paa To the Oil-water Interfacesupporting

confidence: 88%

Ordered polyelectrolyte assembly at the oil–water interface

Beaman

Robertson

Richmond

2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

107

View full text Add to dashboard Cite

Polyelectrolytes (PEs) are widely used in applications such as water purification, wastewater treatment, and mineral recovery. Although much has been learned in past decades about the behavior of PEs in bulk aqueous solutions, their molecular behavior at a surface, and particularly an oil-water interface where many of their applications are most relevant, is largely unknown. From these surface spectroscopic and thermodynamics studies we report the unique molecular characteristics that several common polyelectrolytes, poly(acrylic acid) and poly(methylacrylic acid), exhibit when they adsorb at a fluid interface between water and a simple insoluble organic oil. These PEs are found to adsorb to the interface from aqueous solution in a multistepped process with a very thin initial layer of oriented polymer followed by multiple layers of randomly oriented polymer. This additional layering is thwarted when the PE conformation is constrained. The adsorption/desorption process is highly pH dependent and distinctly different than what might be expected from bulk aqueous phase behavior. macromolecular assembly | surface spectroscopy | water surfaces | hydrophobic surfaces | surfactants

show abstract

Section: Adsorption Of Paa To the Oil-water Interfacesupporting

confidence: 88%

Ordered polyelectrolyte assembly at the oil–water interface

Beaman

Robertson

Richmond

2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

107

View full text Add to dashboard Cite

show abstract

“…The laser system used for the VSF studies has been described elsewhere (36). Briefly, a sum frequency generation spectrometer purchased from Ekspla was used to generate the visible 532-nm beam and the tunable infrared beam.…”

Section: Methodsmentioning

confidence: 99%

Assembly and molecular order of two-dimensional peptoid nanosheets through the oil–water interface

Robertson

Olivier

Qian

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

100

View full text Add to dashboard Cite

Significance Peptoid nanosheets are an emerging class of 2D nanomaterials that have the potential for use in a variety of applications ranging from molecular sensors to artificial enzymes. Because peptoids are highly designable polymers, nanosheets provide a general platform on which to display an enormous diversity of functionalities. Nanosheets are known to form through a unique monolayer compression mechanism, catalyzed by the air–water interface. Here we demonstrate that nanosheets can be formed via adsorption of peptoids at an oil–water interface. Using vibrational sum frequency spectroscopy, we show that electrostatic interactions are essential in the formation of an ordered peptoid monolayer at the interface, a critical intermediate in the nanosheet assembly pathway. These findings open the door for enhancing the complexity and functionality of 2D nanomaterials.

show abstract

“…This system has been described in detail elsewhere. 46 Briefly, a YAG laser outputs 1064 nm pulsed light with an ∼30 ps pulse length. The 1064 nm light is split into two lines, and one line is frequency doubled to give 532 nm light.…”

Section: ■ Experimental Detailsmentioning

confidence: 99%

Metal Ions: Driving the Orderly Assembly of Polyelectrolytes at a Hydrophobic Surface

2012

Self Cite

View full text Add to dashboard Cite

The accumulation of polyelectrolytes at the interface between water and nonpolar fluids is an important process in both environmental and biological systems. For instance, polyelectrolytes such as humic acids are highly charged molecules that play a role in the remediation of water contaminated by oil, and the adsorption of other polyelectrolytes such as proteins and DNA to cellular surfaces is essential in biological processes. The properties of these naturally occurring polyelectrolytes are highly tunable and depend strongly on the binding of metal ions commonly found in environmental and biological systems. While the metal complexation behaviors of many polyelectrolytes and biomolecules are well characterized in bulk solution, this work shows in molecular detail that the behavior of a common polyelectrolyte in the presence of metal ions can be quite different when it adsorbs to a hydrophobic-aqueous liquid interface. In these studies, vibrational sum frequency spectroscopy and interfacial tension measurements conducted on poly(acrylic acid) (PAA) at a model oil-water interface show how small amounts of monovalent and divalent cations significantly alter the interfacial conformation of PAA at the interface and act to enhance its interfacial adsorption. The results provide important new insights that have direct relevance for understanding the effect of metal ions on the adsorption of charged macromolecules to a hydrophobic-aqueous boundary layer, specifically in biological and environmental systems.

show abstract

The Role of Interfacial Molecular Structure in the Adsorption of Ions at the Liquid−Liquid Interface

Cited by 48 publications

References 55 publications

Ordered polyelectrolyte assembly at the oil–water interface

Ordered polyelectrolyte assembly at the oil–water interface

Assembly and molecular order of two-dimensional peptoid nanosheets through the oil–water interface

Metal Ions: Driving the Orderly Assembly of Polyelectrolytes at a Hydrophobic Surface

Contact Info

Product

Resources

About