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Amphiphilic carbon-based nanoparticles have recently attracted much attention in stabilizing Pickering emulsions owing to their low cytotoxicity, cost-effectiveness and biocompatibility. In this work, a facile and aqueous synthesis method was developed for the preparation of amphiphilic graphene quantum dots by modifying hydrophilic GQDs (GQDs-COOH) with hydrophobic hexylamine. Distinctive from pristine GQDs-COOH, amphiphilic GQDs show interesting surface-active properties and can stabilize water-in-cyclohexane Pickering emulsions. As efficient particle surfactants, amphiphilic GQDs could be applied in a mini-emulsion polymerization system to synthesize submicron-sized polystyrene particles. Particularly, the as-prepared PS particles were highly luminescent as produced by the highly fluorescent amphiphilic GQDs.

Adsorption of 5,10,15,20-tetraphenyl-21H,23H-porphyrin cobalt (CoTPP) on mica immersed in organic solvents of 1-hexanol, 1-chlorohexane, and 1-phenyloctane was examined. Flat-lying CoTPP molecules were recognized in topographic images observed by atomic force microscopy. The topographic height of individual porphyrins fluctuated by 0.2 nm in a time scale of 10 s. The height fluctuation was ascribed to two states with and without a solvent molecule trapped in the axial ligand position of the CoTPP. In imaging in phenyloctane, adsorbed CoTPPs were removed by adding 1-hexylamine to the imaging solution. Hexylamine ligands would have occupied the axial position of CoTPP to hinder adsorption. In addition, two-dimensional distribution of force pushing the tip was observed in hexanol to show a layered liquid structure parallel to the mica surface.

In presented paper magnetite nanoparticles (MNP), with various types of surface stabilizers has been fabricated. Nanostructures were obtained by thermal decomposition of Fe(acac)3 precursor in organic solutions. Five types of long-chain carboxylic acids and four types of amines were used for stabilization of nanoparticles. It was also tested, how surfactant concentration influences on the nanoparticles morphology and its properties. Obtained nanoparticles were examined by X-ray diffraction, Transmission Electron Microscopy and Infrared spectroscopy. Magnetic properties of the nanoparticles were tested by Mossbauer spectroscopy and Vibrating Sample Magnetometry. Magnetization and Mossbauer measurements show how stabilizer layer influence the magnetic state of particles. It has been analyzed the importance of the C C chain length, its spatial configuration or compound properties on magnetic state of the particles for few examples. From tested agents as a best, giving most even in shape and well distributed nanoparticles, hexylamine was selected.

Here, solid-stabilized emulsions were developed that were stable for up to one year in both closed test tubes and open air. A complex of silica (aerosil A-380)-hexylamine was used for the emulsions. Both oil-in-water and water-in-oil (O/W and W/O) emulsions were extraordinarily stable, for up to one year when the silica–hexylamine stabilizing complex was incorporated. W/O emulsions formed when the hexylamine volume concentration exceeded that of the silica. If the hexylamine concentration was lower than that of the silica, then O/W emulsions were formed. The emulsion samples maintained their structures, even when exposed to air for a year. When exposed to air, the emulsions dried without destruction of the three-dimensional network of spherical layers of solid particles. A solid nano-microporous material was formed from the reverse emulsion as a result of drying. In the case of direct emulsion drying, the continuous phase (inter-droplet liquid) evaporated while the oil phase remained inside of the droplets.

It is shown experimentally that modification of silica particles by short-chain surfactant like hexylamine leads to inversion of selective wetting angle θ of the particles and to phase inversion in the emulsions stabilized by the hexylamine-modified silica particles. Empiric diagram of emulsion stability shows that at the contact angle θ close to 90° there is region of completely unstable emulsions between regions of stable emulsions of oil-in-water and water-in-oil types in the case of volume fraction of oil O oil = 0.25 or 0.75. At O oil = 0.5 the emulsion type and stability corresponded to the aqueous phase receding and advancing contact angles.

Stable foams have been generated in low concentration aqueous dispersions of hexylamine-modified Laponite particles. The particles are of primary size 30 nm, modified with hexylamine molecules to render them partially hydrophobic or moderate flocculants. Infrared adsorption spectra and zeta potential measurements confirm the adsorption of hexylamine molecules on the Laponite particles. The foamability, drainage behavior and microstructure of wet foams were studied in terms of their dependence on the content of Laponite particles and the concentration of hexylamine. Laser-induced confocal microscopy observations confirm that stable bubbles appear to be surrounded by a thin layer of hexylamine-modified Laponite particles, which is crucial to the stability of foams. The interfacial rheology of the same systems has been also investigated by measuring the dilational viscoelasticity as a function of hexylamine concentrations. The adsorption of particles at the air–water interface has the effect of increasing dilational surface elasticity, indicating that the gel-like layer at the interface inhibits foam drainage and bubble coalescence.

Alkylamines show amphiphilic properties such as self-association in polar solvents and accumulation at interfaces. However, their complexation with alkanoic acids changes drastically their colloidal properties. Phase equilibria at different temperatures in the systems hexanoic acid hexylamine water, heptanoic acid heptylamine water and octanoic acid octylamine water were determined in order to elucidate the structure in the isotropic solution phases. Densities, surface tensions, electrical conductivities and viscosities were measured at 298.2 K. Self-diffusion coefficients were also determined both in the acid- and in the amine-rich part of the phase diagram in order to confirm if a component is confined to closed aggregates. The aim of this study was to contribute to a better understanding of the complexation in relation to the properties of catanionic surfactants.