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Preparation of polylactide microcapsules at a high throughput with a packed‐bed premix emulsification system
Author(s) -
Sawalha Hassan,
Sahin Sami,
Schroën Karin
Publication year - 2016
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.43536
Subject(s) - membrane emulsification , materials science , polymer , packed bed , chemical engineering , membrane , composite material , chromatography , emulsion , chemistry , biochemistry , engineering
Core–shell polymer microcapsules are well known for their biomedical applications as drug carriers when they are filled with drugs and gas‐filled microcapsules that can be used as ultrasound contrast agents. The properties of microcapsules are strongly dependent on their size (distribution); therefore, equipment that allows the preparation of small and well‐defined microcapsules is of great practical relevance. In this study, we made polylactide microcapsules with a packed‐bed premix emulsification system that previously gave good results for regular emulsions. Here, we tested it for applicability to a system in which droplets shrank and solidified to obtain capsules. The packed‐bed column was loaded with glass beads of different sizes (30–90 µm) at various bed heights (2–20 mm), and coarse emulsions consisting of the polymer, a solvent, and a nonsolvent were pushed repeatedly through this system at selected applied pressures (1–4 bar). The obtained transmembrane fluxes (100–1000 m 3 m −2 h −1 ) were much higher than those recorded for other membrane emulsification techniques. The average size of the obtained microcapsules ranged between 2 and 8 µm, with an average span of about 1; interestingly, the capsules were 2–10 times smaller than the interstitial voids of the beds. The droplets were larger when we used thicker beds and larger glass beads, and these effect correlated with the pore Reynolds number (Re p ). Two breakup mechanisms were identified: spontaneous droplet snap‐off dominated the system at low Re p s, and localized shear forces dominated the system at higher Re p . © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43536.