Dynamic membrane

The specification relates to thin, minute foils of a synthetic material obtained by an interfacial polycondensation reaction. More specifically, a process is described in which one reactive compound is dissolved in a non-aqueous solvent that has a boiling point below the boiling point of water. A second reactive compound is dissolved in water and the non-aqueous phase is then dispersed in the aqueous phase. A polycondensation reaction takes place at the interface of the two phases resulting in the non-aqueous phase being encapsulated by the polycondensation reaction product. The dispersion of the encapsulated non-aqueous phase in the aqueous phase is then heated to a temperature above the boiling point of the non-aqueous phase, but below the boiling point of water. The heating causes the encapsulating polymer to burst and to form thin, minute polymeric foils. The foils may be used directly or after some purification treatment for the formation of a dynamic membrane.