Recent studies have shown that bubbles inside a volatile liquid can spontaneously grow in the absence of bulk gas supersaturation through diffusion of air driven by differences in its partial pressure. Here, we demonstrate a distinct manifestation of this phenomenon in which perfluorocarbon oil-shell bubbles, formed following bubble detachment from a perfluorocarbon oil (PP1, F2 Chemicals)–water interface, become trapped and spontaneously expand at the water–air interface. Addition of the anionic fluorosurfactant Capstone FS-60 to the aqueous phase stabilizes the detached oil-shell bubbles at the water–air interface. The bubbles spontaneously grow from an initial diameter of approximately 1.5 mm to several millimeters within a few minutes. The initial growth rate reaches about 11 μm/s, substantially exceeding that observed for bubbles trapped at the PP1–water interface. Bubble-bursting measurements indicate progressive thinning and eventual depletion of the PP1 shell at bubble radii of approximately 2.5–3.0 mm. Bubble growth nevertheless continues after shell depletion as the system transitions into a surfactant-stabilized foam bubble containing PP1 vapor. An interfacial air-diffusion model attributes the enhanced growth to the short diffusion path across the thin liquid film separating the bubble from the atmosphere, driven by the difference in air partial pressure between the PP1-vapor-containing bubble interior and the surrounding atmosphere. Finally, multiple oil-shell bubbles form self-expanding foam clusters that continue to grow for hours, increasing their apparent foam volume by more than 2 orders of magnitude. These findings demonstrate how modifying the mass-transfer geometry of interfacial air diffusion can strongly accelerate bubble growth and enable the formation of self-inflating bubbles and foams under ambient conditions.

The polyglycerol esters (PGEs) of fatty acids have a wide range of HLB values and applications in diverse industries, such as pharmaceuticals and cosmetics. While the physicochemical properties of oil-soluble PGEs dissolved in oil phases are well studied in the literature, there is no information on their structuring in aqueous phases and emulsifying abilities. We combined rheological and differential scanning calorimetry (DSC) measurements and microscopy observations to characterize the dependence of oil-soluble PGE structuring in aqueous phases on the PGE concentration, the temperature of solution homogenization, and the PGE molecular structure. Excellent correlations between the considerable changes in solution viscosity and the temperatures of the two endo- and exothermic peaks in the DSC thermograms are observed. Single-tail PGE molecules, which have a higher number of polyglycerol units, are better organized in networks, and the viscosity of their aqueous solutions is higher compared to that of the respective double-tail PGE molecules. PGEs exhibit good emulsifying ability and the viscosity of the produced emulsions at room temperature can differ by orders of magnitudes depending on the temperature of emulsification. The reported properties of oil-soluble PGEs could be of interest for increasing the range of their applicability in practice.

The shear rheology of linear wormlike micellar solutions (WMSs) is described by both Poisson renewal (PRM)and shuffling (SFM) models with different values of the model parameters. For low shear strains and rates ofstrains, the micellar solutions behave as a Maxwellian body with constant elasticity and viscosity. The excellentdescription of experimental data in the literature using PRM or SFM suggests that both models predict identicaldependencies of the dynamic storage and loss moduli on the frequency of oscillations. It is shown in the literature, that the PRM becomes equivalent to the SFM, when the breaking time is constant, τbr, and the characteristic reptation time, τrep, is equal to π2 τd0, where τd0 is the reptation time evaluated with respect to the average length of the chain. Three independent rheological tests (apparent viscosity vs shear rate, stress vs strain at constant shear rates, strain oscillations at low amplitudes and different frequencies) are applied to low, medium, and high zero-shear viscosity WMSs to obtain the PRM and SFM model parameters (elasticity, viscosity, relaxation, breaking, and reptation times). The known closed-form analytical expression for the Laplace image of the stress relaxation function and the respective infinite series for the complex modulus give possibility for the reported here precise systematic calculations of the storage and elastic moduli, the crossover frequency, and the elasticity for all values of ζbr = τbr/τrep ≤ 100. The predictions of the PRM length-dependent breaking-time versions are indistinguishable from those of the SFM for the obtained universal dependencies of the characteristic time, τB0, on ζbr. The applicability of the Vasquez–Cook–McKinley and the single-mode Oldroyd 8-constant models to describe the rheological behavior of WMSs is tested. The theoretical findings and conclusions are confirmed experimentally and illustrate the self-consistency of the used rheological regimes.

Laboratory 6.2 “Disperse systems and rheology in clean technologies” within WP 6 “Nano-structured materials and disperse systems in clean technologies” aims at the development of new systems for clean technologies and nanotechnologies in various scientific and technological areas: new cleaning agents for hard surfaces; encapsulation and controlled release of reagents; wetting and dewetting processes. The main objectives are to conduct experimental and theoretical research and development of new dispersed systems through the inclusion of new raw materials and innovative materials, and to develop and apply theoretical models of the interactions and stability of complex dispersed systems. High scientific output of Lab 6.2 is manifested via 21 scientific publications in the fields of Dispersion Chemistry, Chemical and Materials Sciences for the period 2018 – 2024 (8 articles in Q1 journals, 6 in Q2, and 7 materials in Q4). Optimized compositions of cleaning formulations for hard surfaces with sulfonated methyl esters have been obtained [1]. New theoretical models for the interactions that determine the structures in micellar systems have been developed and applied [2]. New phenomena such as vortexing [3] and nanoemulsification [4] have been described. New methods have been proposed for obtaining emulsions and foams from triglyceride phases [5]. The role of the components and compositions for the rheology [6], wetting, and cleaning [7] has been demonstrated.