Permeability of lipid-coated polymer capsule membranes to solutes: Effects of temperature and chemical structure of solutes

Abstract

The permeability of di-stearyldimethylamrnonium-coated polyamide capsule membranes to KCI, and tetra-methylammrnonium (4C₁N), tetrapropylammonium (4C₃N), and tetra-butylammonium (4C₄N) bromides was investigated at temperatures below and above the phase transition temperature of the amphiphile coat and compared with that of non-coated polyamide capsule membranes. The rate of solute permeation through the non-coated capsule membranes for all permeants increased gradually with rise in temperature. When the capsule was coated with the amphiphile, the rate was reduced by a factor of 2–200 relative to that through the non-coated semipermeable capsule membranes and changed drastically or slightly at the phase transition temperature of the amphiphile coat, depending on the chemical structure of permeants. The permeation of hydrophilic KCl and slightly hydrophobic 4C₁N was greatly supressed by the amphiphile coat below the phase transition temperature while it was enhanced above that temperature. On the contrary, the permeation rate of the moderately hydrophobic and bulky 4C₃N increased monotonically with rising temperature. No change in the permeation rate was observed with the highly hydrophobic and bulky 4C₄N at all temperatures.

Key Words:

• Polyamide
• Permeability
• lipid-coated
• capsule
• microcapsule