The synthesis of semipermeable membrane microcapsules using in situ cyanoacrylate ester polymerization.

A new material for the microencapsulation of biological systems was discovered and characterized with regards to the effects of reaction conditions on product yield. By using poly(cyanoacrylate ester), membrane microcapsules were produced with sufficient strength and porosity to be effective in a process environment for the immobilization and protection of encapsulated material. After synthesizing numerous monomeric cyanoacrylate esters, the n-butyl derivative was discovered to give the best results with regards to microcapsule formation. Microcapsules were prepared by a droplet technique in which an aqueous solution is sprayed into an organic solvent containing the cyanoacrylate ester monomer. By pre-treating the cyanoacrylate ester monomer with an anion exchange resin (Amberlyst A-21, Rohm and Haas, Philadelphia, USA), a significant reduction in the amount of acidic impurities which can adversely affect results was achieved. The use of polyvinylpyrrolidone as a polymerization initiator gave the best results of a variety of polymeric and non-polymeric initiators investigated. Successful encapsulations were achieved using a solvent mixture of 60% (v/v) iso-octane/40% trichloroethylene, 0.1% (w/v) polyvinylpyrrolidone initiator, pH 6.5 aqueous encapsulation solution, and 5% (v/v) methylcyanoacrylate/A-21 treated n-butylcyanoacrylate (added separately to solvent) made to a 4% (v/v) solution in solvent. Ester monomers were synthesized and used to prepare polymer membranes.