Biodegradable hollow poly-lactic acid (PLA) microcapsules and hollow polyelectrolyte microcapsules made of poly-allylamine hydrochloride (PAH) were synthesized by directly adsorbing these polymers to N2 (air) and CO2 microbubbles respectively, using the bubble template method. To manufacture PLA microcapsules, droplets of a solution of PLA in methylene chloride (CH2Cl2) were emulsified in water. Then by solvent diffusion, N2 microbubbles nucleated inside the droplets and PLA adsorbed to the bubble surface to form microcapsules. Likewise, for PAH microcapsules, when an aqueous solution of Na2CO3 including PAH is titrated with HCl, within a specific range 7.5 < pH < 9.0, colloidal PAH particles are formed and then adsorbs to the nucleated CO2 microbubbles. This yields to hollow PAH microcapsules. If the solution pH is outside this range, colloidal particles can no longer exist, thus no microcapsules can be synthesized. This document mainly focuses on size control of these two types of microcapsules.

This content is only available via PDF.
You do not currently have access to this content.