Preparation of microcapsules and control of their morphology

• Published in: Journal of microencapsulation Vol. 20; no. 4; pp. 497 - 508
• Main Authors: Kiyoyama, S., Shiomori, K., Kawano, Y., Hatate, Y.
• Format: Journal Article
• Language: English
• Published: Colchester Informa UK Ltd 01.07.2003; Taylor & Francis; Informa
• Subjects: Biocompatible Materials; Biodegradable Microcapsules; Biological and medical sciences; Capsules - chemistry; Cross-linked Microcapsules; Drug Carriers - chemistry; Drug Compounding - methods; Drug Delivery Systems; Emulsions; Entrapment Efficiency; General pharmacology; Humans; Medical sciences; Microscopy, Electron, Scanning; Microspheres; Morphology Control; Particle Size; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Polymers - chemistry; Solubility; W/O/W Emulsion; Encapsulation; Pharmaceutical technology; Cross-linked microcapsules; entrapment efficiency; Microcapsule; morphology control; Polymerization; Drug carrier; biodegradable microcapsules; Salt effect; Morphology; Water oil water emulsion; Dosage form; W/O/W emulsion
• ISSN: 0265-2048; 1464-5246
• DOI: 10.1080/0265204031000093096

For the preparation of microcapsules using the W/O/W (water in oil in water) emulsion system, it is essential to control various factors such as the dispersed state of the organic phase in the W/O/W emulsion, the difference in the solute concentration between the inner and outer aqueous phases and the volume fraction of the dispersed phase. In this study, cross-linked microcapsules were prepared by the in-situ polymerization of styrene and divinylbenzene and biodegradable microcapsules were prepared by the solvent evaporation method. The effects of the preparation conditions on the capsule morphology and entrapment efficiency of water-soluble materials were investigated. The average diameter of the surface pores and internal hollows were controlled on a sub-micron order by changing the preparation conditions such as diluent concentration, volume fraction of the dispersed droplets in the W/O (water in oil) emulsion, surfactant concentration monomer ratio and salt concentration in the outer aqueous phase. Furthermore, the water-soluble materials were completely entrapped in the biodegradable microcapsule by changing the preparation conditions such as volume fraction of the dispersed droplets in the W/O emulsion, salt concentration in the inner and outer aqueous phases, polymer concentration and supersonic irradiation of the W/O droplets.