| abstract |
A two step interfacial polymerization process for encapsulating operative chemically active substances in high quality semipermeable membranes. An emulsion is formed wherein the discontinuous phase contains the substance to be encapsulated and a first monomer. When a second monomer is added to the continuous phase, an imperfect membrane forms about the droplets of the discontinuous phase. Removal of the continuous phase, followed by resuspension of the raw microcapsules and addition of a second portion of second monomer, causes further polymerization strengthening the membranes and "patching" macroporous defects in them. The choice of solvents and control of reaction conditions such as pH, maximize the yield of operable labile substance encapsulated. A method of encapsulating a very high concentration of hemoglobin is also disclosed. Adaption of the two step process provides a method for forming and controlling the pore sizes in the membranes of a number of known prior art encapsulation processes. |