Kahefaasilised

Kahefaasilised is an Estonian term used in science to denote a system or material consisting of two distinct phases with limited mutual solubility, i.e., a biphasic or two-phase state. The word derives from kahe (two) and faas (phase) with the suffix -ilised (adjectival). In English, it corresponds to biphasic or two-phase.

In chemistry and materials science, kahefaasilised systems include liquid–liquid biphasic mixtures such as oil and water, two-phase polymer blends, or solid–liquid systems where a dispersed phase coexists with a continuous phase. In liquids, the two phases form an interface and exhibit distinct compositions and properties. The phase volumes, interfacial tension, and droplet size distributions govern mass transfer and stability. In biology or medicine, biphasic delivery formulations may release active ingredients across two phases or compartments.

Typical examples include oil-in-water and water-in-oil emulsions, two-phase solvent extraction, and gas–liquid or liquid–solid two-phase flows in industrial processes. Such systems are studied for their stability, phase behavior, and transport properties, as well as for their applications in separation technologies, cosmetics, foods, and pharmaceutical formulations.

Analytical approaches used to characterize kahefaasilised systems include optical and confocal microscopy to observe the interface and phase distribution, differential scanning calorimetry and rheology to assess properties of each phase, and interfacial tension measurements to quantify the forces at the boundary between phases.

See also: biphasic, multiphase, emulsion, two-phase system.