TiO₂-based materials are of great practical interest in several technological areas. Both the size and the morphology of the TiO₂ particles are of critical importance for their applications. The current study explores the effect of several factors on the outcome of the TiO₂ particle synthesis via the so-called ‘two-emulsion method’. In this technique, two water-in-oil emulsions—each of them containing different reactant in the dispersed water drops—are mixed under well controlled conditions. Upon such mixing, partial coalescence of the water drops from the two emulsions leads to mixing of the drop content, with chemical reaction occurring within the drops, and to synthesis of Ti(OH)₄ particles. Afterwards, the latter are transformed by emulsion heating into TiO₂ particles and aggregates of predominantly anatase structure. Our results show that—depending on the precursor and surfactant concentrations, oil viscosity, emulsification time, and mixing speed—the obtained nanoparticles could aggregate either on the drop surface, forming capsules with a very smooth surface, or inside the water droplets, thus leading to hierarchically structured aggregates of micrometer size. The spherical smooth capsules are constructed of very small monodisperse TiO₂ nanoparticles with size below 5 nm. The hierarchical bulk aggregates, on the other hand, are formed from bigger primary particles of sub-micrometer size. The obtained results show that one can obtain various TiO₂ structures by controlling the conditions during the emulsion preparation and mixing

This study investigates composition-microstructure-rheology-performance relationships in Carbopol-based emulgels and bigels containing different oils. Optical microscopy revealed polydisperse droplets in liquid paraffin, isopropyl myristate, and almond oil formulations, whereas cetyl alcohol systems exhibited larger, irregular birefringent particles with Maltese cross-like patterns. All formulations showed shear-thinning behavior and predominantly elastic responses (G′ > G″). Cetyl alcohol-based emulgels exhibited higher elastic moduli and viscosity than those containing other oils. Increasing Carbopol concentration from 0.5% to 1% enhanced elasticity and viscosity, while reducing viscosity losses during heating from 10 to 40 °C from 35 to 40% to 11–26%. Bigels containing 20% and 30% oleogel exhibited elastic moduli approximately 20% and 80% higher than the hydrogel, respectively, suggesting possible synergistic mechanical reinforcement. Correlation analysis revealed relationships between rheological parameters, drug release, and spreadability. Viscosities above approximately 150 Pa·s were associated with reduced drug release, while moderate viscosity favored a balance between structural integrity, spreadability, and release performance. The absence of visible changes after 12 months of storage was consistent with temperature-ramp rheology results, suggesting potential use as a preliminary screening tool for formulation stability. Overall, oil phase selection, phase structuring, and Carbopol concentration enable tailoring stable and functional emulgel and bigel formulations for pharmaceutical and cosmetic applications.