The interactions between the adsorbed molecules on the oil-water interface at various salt concentrations

Wang, Jingmin; Hou, Yi; Chen, Shunli; Wu, Xingxing; Yuan, Qunhui; Gan, Wei

doi:10.1016/j.molliq.2019.110907

Cited by 7 publications

(2 citation statements)

References 54 publications

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“…The same selection rule described above applies to VSFG and allows it to obtain chemical structural information on buried interfaces based on vibrational modes of specific chemical functional groups. Due to their interfacial selectivity, both VSFG and optical SHG serve as powerful tools and have been utilized to probe various planar and colloidal surfaces, including liquid–liquid neat oil/water and oil/surfactant/water interfaces. − In fact, they have been used to investigate various physicochemical properties of emulsions. Herein, we briefly review some of these studies to highlight the significance of interfacial NLO techniques in elucidating structures and processes at emulsion interfaces.…”

Section: Introductionmentioning

confidence: 99%

Molecular Adsorption and Physicochemical Properties at Liquid/Liquid Nanoemulsion Soft Interfaces: Effect of Charge and Hydrophobicity

Sara,

Coers,

Behrman

et al. 2024

J. Phys. Chem. B

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Contrary to the popular adage, "Oil and water do not mix", evidence of mixtures comprising the two "immiscible" liquids is universal. In the presence of an emulsifier, oil and water mix to form a colloidal suspension known as emulsion. Their utility in many areas such as food chemistry, biomedical health sectors, catalysis, and the petroleum industry is well recognized. While their application in our society is pervasive, tantalizing fundamental questions regarding the chemistry that takes place at the oil/water soft interface still linger. For instance, do organic compounds show proclivity for this molecularly thin boundary and, if so, what forces, hydrophobic or pure electrostatic among others, drive the molecular interactions? The focus of this Article is on molecular adsorption at the interface of oil-in-water (O/W) nanoemulsion (NE) droplets. The effect of the interfacial surfactant charge (positive, negative, zwitterionic, and neutral) on the affinity of aromatic organic compounds on the O/W NEs has been studied. Using a second harmonic generation (SHG), a nonlinear light scattering technique, we have explored the adsorption equilibrium of charged and neutral organic dyes. By variation of the surfactant functional group and thereby the interfacial charge properties, the source of the adsorption interaction, if any, has been deduced. The population of surfactants containing a charged functional group at the O/W interface is found to be sparse, yet adsorption at some of these interfaces has been observed. A purely electrostatic Coulomb interaction plays a key role, but the presence of a charged interface does not necessitate molecular adsorption. Hydrophobic interactions are not a major driving force of adsorption for the SHG dyes studied. However, a possible pi-interaction is likely in explaining the accumulation of neutral aromatic compounds at the O/W NE interface. These intricate adsorption features are discussed in the context of NE interfacial charge properties and their stability upon molecular adsorption.

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Section: Introductionmentioning

confidence: 99%

Molecular Adsorption and Physicochemical Properties at Liquid/Liquid Nanoemulsion Soft Interfaces: Effect of Charge and Hydrophobicity

Sara,

Coers,

Behrman

et al. 2024

J. Phys. Chem. B

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“…SHG signals may be enhanced by the resonant enhancement effect when dye molecules with noncentrosymmetric structures and high hyperpolarizability (β) are excited by lasers at proper wavelengths. , For many dyes, TPF signals are also produced upon excitation by a laser with high peak power, which may influence the accuracy for determining the SHG signal and for multimodal imaging . In previous studies, MG (malachite green) and D289 (( E )-4-(4-(diethylamino)styryl)-1-methylpyridin-1-ium) were commonly used as SHG-active molecules. − MG has a relatively high SHG efficiency and low TPF emission, so it has been used in studying energetics during its adsorption and interactions with interfaces, including gas–solid, gas–liquid, solid–liquid, and water lipid interfaces. , It is also known that MG has a higher SHG efficiency in acidic bulk solutions (pH = 4); D289 is suitable for use in neutral environments, which better resembles the biological environment. ,,, It was observed that D289 emitted a strong TPF signal, especially when it was dispersed in lipid membranes, , although this TPF differs in wavelength from the SHG emission and can be separated in spectral measurements. It is known that dyes emitting strong fluorescence may generate unwanted fluorescence backgrounds and cross-modal interference when used in multiple imaging systems, ,, which could decrease the resolution of images in a large scale.…”

Section: Introductionmentioning

confidence: 99%

Modification of the Second Harmonic Generation and Fluorescence Efficiency of D289 Dye Based on a Donor–Acceptor Structure

Peng

Hou

et al. 2022

J. Phys. Chem. C

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Second harmonic generation (SHG) spectroscopy and microscopy have been widely applied in studying the interfacial processes that occur in chemical, physical, and biological systems. Efficient SHG probes are crucial for these investigations. Herein, we designed two water-soluble dyes with conjugated donor–acceptor structures (TPAP and TPAPM) and studied their second-order nonlinear optical (NLO) properties and fluorescence efficiencies. The modified molecules emitted much less two-photon fluorescence than dye D289 due to nonradiative transitions caused by molecular motions in solution. TPAPM exhibited higher NLO performance than D289 and TPAP because of the strong electron pull–push effect operating along the D−π–A backbone, and it is a promising SHG probe molecule for multimodal imaging in biological applications.

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In Situ Spectroscopic Probes for Structures and Processes at the Surface of Noble Metallic Nanoparticles

Xue

Guha

Yuan

et al. 2021

Part & Part Syst Charact

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The interactions between the adsorbed molecules on the oil-water interface at various salt concentrations

Cited by 7 publications

References 54 publications

Molecular Adsorption and Physicochemical Properties at Liquid/Liquid Nanoemulsion Soft Interfaces: Effect of Charge and Hydrophobicity

Molecular Adsorption and Physicochemical Properties at Liquid/Liquid Nanoemulsion Soft Interfaces: Effect of Charge and Hydrophobicity

Modification of the Second Harmonic Generation and Fluorescence Efficiency of D289 Dye Based on a Donor–Acceptor Structure

In Situ Spectroscopic Probes for Structures and Processes at the Surface of Noble Metallic Nanoparticles

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