Model capsules I.: Synthesis, characteristics and properties of millimetric polyamide capsules

Polyamide model capsules (millicapsules) are synthesized by interfacial polymerization. An adapted apparatus has been perfected in order to obtain easy handling capsules (diameter between 1.2 and 4.5 mm) with or without surfactant. The polymer weight composition with regard to the capsule mass, the influence of the surfactant, the growing time and the concentration and the nature of the reagents on the thickness and the surface state of the capsules wall are determined. SEM observations of the internal and external surface of the membrane allows one to follow the progress of its development as a function of the polymerization time. Measurements of the permeability by macromolecules crossing through the millicapsules membrane as well as mechanical resistance by determination of the rupture strength have been made on well-defined capsules. (C) 1999 Elsevier Science BN. All rights reserved.