Effect of long-chain alcohols on SDS partitioning to the oil/water interface of emulsions and on droplet size

Effects of Fatty Alcohols with Different Chain Lengths on the Performance of Low pH Biomass-Based Foams for Radioactive Decontamination

Compared with polymers and nanoparticles, fatty alcohols can not only increase the stability of foam, but also maintain better foamability at pH < 2, which is beneficial to reduce waste liquid and increase decontamination efficiency for radioactive surface pollution. However, different fatty alcohols have different hydrophobic chain lengths. The effects of fatty alcohols with different chain lengths on the performance of decontamination foam were studied at pH < 2, to assist in the selection of suitable fatty alcohols as foam stabilizers. Combined with betaine surfactant and phytic acid, biomass-based foams were synthesized using fatty alcohols with different chain lengths. When the hydrophobic tail groups of the fatty alcohol and the surfactant were the same, the foam showed the best performance, including the lowest surface tension, the highest liquid film strength, the greatest sag-resistance and the best stability. However, when the hydrophobic tail groups were different, the space between adjacent surface active molecules was increased by thermal motion of the excess terminal tail segments (a tail-wagging effect), and the adsorption density reduced on the gas-liquid interface, leading to increased surface tension and decreased liquid film strength, sag-resistance and stability. The use of decontamination foam stabilized by fatty alcohols with the same hydrophobic group as the surfactant was found to increase the decontamination rate of radioactive uranium pollution from 64 to over 90% on a vertical surface.

Effect of Surfactants on the Molecular Structure of the Buried Oil/Water Interface

The oil/water interface, for instance in emulsions, is often stabilized by surfactants. Hence, the co-existence of oil, water, and surfactant molecules at the buried oil/water interface determines macroscopic properties such as surface tension or emulsion stability. Utilizing an inherently surface sensitive spectroscopic method, sum frequency generation (SFG) spectroscopy, we show that adsorption of an anionic surfactant to the buried oil/water interface increases the magnitude of the interfacial electric field. Meanwhile, the degree of ordering of the interfacial oil molecules increases with the surfactant concentration owing to the intercalation of aliphatic chains of interfacial oil and surfactant molecules. At sufficiently high surfactant concentrations, the interfacial charge reaches a maximum value and the interfacial oil molecules arrange in a fully ordered conformation, a state which coincides with the significant decrease in interfacial tension and increased emulsion stability.

Magnetic Microemulsions Stabilized by Alkyltrimethylammonium-Based Magnetic Ionic Liquids Surfactants (MILSs)

While traditional microemulsions are versatile media for nanoscience and nanotechnology, stimulus-responsive microemulsions are more challenging to realize, and only a handful of cases have been reported. We here introduce magnetic microemulsions (MMEs) stabilized by alkyltrimethylammonium-based magnetic ionic liquids surfactants (MILSs), paired with water as the polar phase, aliphatic oils as the nonpolar phase, and aliphatic alcohols as the cosurfactant. n-Hexane coupled with n(MILSs/1-butanol) = 1:4 showed the most excellent ability to form MMEs, and the range of the monophasic region was expanded with increasing alkyl chain length of MILSs cation. Classical oil-in-water (O/W), bicontinuous (BC) sponge structure, and inverse water-in-oil (W/O) subregions were clarified by conductivity method. Dynamic light scattering showed that the diameter of W/O microemulsions droplets were about 2-6 nm. Magnetic susceptibility and rheological measurements revealed that these MMEs are with high magnetic susceptibility and low viscosity, which show interesting potential applications based on a manipulation via external magnetic field. Moreover, these MMEs showed Newtonian-like flow behavior within respective subregions, and their magnetic susceptibility was not affected by the subregion structure but MILSs mass fraction.

Phase behaviors and characterization of magnetic microemulsions containing pentaalkylguanidinium-based magnetic room-temperature ionic liquids (MRTILs)

Strong magnetic susceptibility and low viscosity magnetic microemulsions containing pentaalkylguanidinium-based magnetic room temperature ionic liquids.

Diazoresin modified monodisperse porous poly(glycidylmethacrylate-co-divinylbenzene) microspheres as the stationary phase for high performance liquid chromatography

Diazoresin modified monodisperse porous PGMA–DVB microspheres were used as a novel tool for the separation and purification of the N-vinyl-1,2,4-triazole product from its by-product was developed.

Experimental and molecular dynamics investigation into the amphiphilic nature of sulforhodamine B

Sulforhodamine B (SRB), a common fluorescent dye, is often considered to be a purely hydrophilic molecule, having no impact on bulk or interfacial properties of aqueous solutions. This assumption is due to the high water solubility of SRB relative to most fluorescent probes. However, in the present study, we demonstrate that SRB is in fact an amphiphile, with the ability to adsorb at an air/water interface and to incorporate into sodium dodecyl sulfate (SDS) micelles. In fact, SRB reduces the surface tension of water by up to 23 mN/m, and the addition of SRB to an aqueous SDS solution induces a significant decrease in the cmc of SDS. Molecular dynamics simulations were conducted to gain a deeper understanding of these findings. The simulations revealed that SRB has defined polar "head" and nonpolar "tail" regions when adsorbed at the air/water interface as a monomer. In contrast, when incorporated into SDS micelles, only the sulfonate groups were found to be highly hydrated, suggesting that the majority of the SRB molecule penetrates into the micelle. To illustrate the implications of the amphiphilic nature of SRB, an interesting case study involving the effect of SRB on ultrasound-mediated transdermal drug delivery is presented.