Peeling back the layers: Investigating the effects of polyelectrolyte layering on surface structure and stability of oil-in-water nanoemulsions

A decade of developing applications exploiting the properties of polyelectrolyte multilayer capsules

“…Oil droplets produced by such emulsions can be coated by thin polyelectrolyte shells and suspended in an aqueous medium to fabricate microcapsules serving as carriers of various agents. [125][126][127][128][129][130] Lee et al developed a method to fabricate stimuli-responsive polyelectrolyte microcapsules in one step based on nanoscale interfacial complexation in emulsions. This one step method extends the utility of polyelectrolyte microcapsules and overcomes the major challenges that are presented by conventional polymeric microcapsule preparation techniques.…”

Responsive Material and Interfacial Properties through Remote Control of Polyelectrolyte–Surfactant Mixtures

“…In fact, so far, P/S mixtures can only change their properties under somewhat harsh chemical conditions. This is because the main driving forces for P/S association in the bulk are predominantly electrostatic interactions paired with weaker hydrophobic and dispersive interactions. , For classical surfactants, the hydrophobic part cannot be changed reversibly while the electrostatics are dependent, e.g., on the choice of electrolyte and its ionic strength . As we will show below, the use of photoswitchable surfactants allows us to control the binding of polyelectrolyte and surfactants reversibly, which can be triggered by light irradiation and subsequent E / Z photoisomerization and which we now apply to modify both colloidal and interfacial properties of P/S mixtures on demand.…”

Nanoscale Effects on the Surfactant Adsorption and Interface Charging in Hexadecane/Water Emulsions

“…Clearly, this provides a basis for systematic investigations of interfacial electrostatics as well as the interfacial molecular structure as a function of the particle size down to the nanoscale and many other effects. 8,9 Although the knowledge of the interfacial molecular structure and the charging state in emulsions is of great importance, most of the existing knowledge arises from experimental data of extended o/w interfaces because they can be more easily accessed with a large variety of complementary methods such as surface tensiometry, 10,11 ellipsometry, 12 and nonlinear optical spectroscopy 13−19 as well as with theoretical simulations. 16,20−23 The results from extended o/w can explain reasonably well the behavior of macroemulsions since the curvature of the droplet is large enough compared to molecular dimensions and to the relevant Debye lengths of interfacial double layers when charged oil droplets are considered.…”

“…In fact, in emulsions the ubiquitous o/w interfaces can be easily changed by changing the bulk compositions of either the continuous or the dispersed phase and are, thus, tunable by the rich variety of available emulsifiers like surfactants and polyelectrolytes as well as by different oil phases. Clearly, this provides a basis for systematic investigations of interfacial electrostatics as well as the interfacial molecular structure as a function of the particle size down to the nanoscale and many other effects. , …”

“…This lack of information on a molecular level is due to a lack of experimental methods that can be applied in situ to the internal interfaces of emulsions. Investigations on emulsion droplets and planar o/w interfaces performed with high-resolution methods, e.g ., neutron and X-ray scattering or nonlinear optical light scattering, ,,− are compared to the available information from extended interfaces, in fact, scarce. Often, the experimenter is limited to extended surfaces and has to assume that conclusions from the latter are transferable to droplet surfaces.…”